Windows 7

It should be noted that most DLL files are subject to copyright, and redistribution legalese. Meaning, they typically come with a product such as Microsoft Windows or Word or what-not, and there is legal language in place that makes unsolicited redistribution illegal in many cases. Whenever you distribute any form of computer software (including DLLs), or whenever you obtain such software other than from the original vendor, you are likely to violate the law.

Also: Before replacing them, you might want to try (in XP):

start / run: SFC /scannow
(the system file checker will look for corrupted / invalid dll's and replace them from your windows CD ... )

Here are some advantages and disadvantages as stated by vistahunt.com:

Windows Vista Advantages:1. Improved Graphical User Interface, the Aero:There is an entire new GUI for Windows Vista. The appearance of window, desktop, start button, start menu, taskbar, everything got a new look. Now, the window in Windows Vista looks similar to that of in Mac OSX. Minimize, maximize and the close buttons wore an entire new strange look. The windows can be made to appear in translucent, 3D modes, if the new Aero is applied. The start button has been modified to give a new look. The word "start" has been removed. Only the new Windows logo gets appear in start button. Start menu also got a new look. The desktop wallpapers got a new look too. The desktop contains a side bar, which shows a clock, and some of the widgets. Widgets are small programs, which is equivalent to standard short cuts. 2. Surf the net, without much worry about securityBrowsing the net, without any security measures invites a major danger. Windows Vista enable one provide high level of security measures. Windows Vista has come with a latest version of Internet Explorer which is version 7.0. This provides a higher degree of security to the system, as well as, the operating system environment. It also warns strictly against visiting some fake sites. It includes phishing filter to provide higher security while surfing the net. Protection against spamming is also provided. The other security measures include tools such as Windows defender, advanced firewall, Encryption/Decryption of data, support for NTFS partitions, auto backup. The Windows Defender is a program which blocks suspicious programs which tries to do some illegal activity in the computer system. Advanced firewall provides security to both incoming and outgoing data. 3. Manage your knotty kids, using parental controls:One can control kids by using parental controls in Windows Vista. Parents can now deny access to certain programs especially, the games. Through separate child account, parents can now keep track of what all activities done by the child. It also enables parents to control the activities by blocking certain activities such as running a game program, blocking some sites that, the child might have visited etc. For this to work, parent must setup separate account for the child with different password. 4. Play multimedia contents using latest media player:The latest version of Windows Media Player bundled with Windows Vista. The Windows Media Player 11 enhances video, audio quality when playing sound, music, videos. It has got new look and has got a series of rich features. These features include URGE services from MTV digital music services, Simplified Library, Library layouts. The newest URGE services provide access to the huge collection of online music, song collections. The simplified library improves customization options. Whenever, one plugs some of the latest media player compatible devices, the media player detects the device and installs the drivers associated with the device automatically. 5. Improved search, Windows Explorer:In Windows Vista, you will get the search result as and when you type some letters of a particular word. The explorer shows a list of all files in the folder by default. When one types in, the few letters of words in the search box, the files will get filtered out according to the letters. Suppose, if one searches for filenames of "govt. services", the search will filter out and displays only files with filenames with the name "gov", if you type "gov" in the search text box. It will further filter the filenames, when you type full form. Also, the look of Windows Explorer got changed rapidly. More sorting options are also provided. Different kinds of listing is also got introduced. 6. Date and time, know the difference in time across the world:In earlier Windows operating systems, it was indeed difficult to know the time difference across the two countries. It proved difficult for online chat users. In Windows Vista, one can add additional clocks, to show the time of some other country. For example, if you want to know the time of London, then you can add clock of London to the additional clocks tray. The tray comes up for display, when one moves mouse over the time shown in the task bar. 7. Manage your photos using photo gallery:Windows Vista has got an inbuilt tool called as Photo Gallery to manage digital photos. Using it, one can modify the photos. It has got ability to show previews of movie files, a feature, which was not there with Windows XP. Using this tool, one can transfer or share the photos from computer to devices such as mobile phones, PDA's, etc. The photo gallery also has the ability to work high precision, high quality images, which are produced by latest high quality cameras. 8. Total different world, new experience:Windows Vista brings you the new world of new experience. It starts from amazingly changed desktop, which goes beyond imagination. All icons look better this time around. The 256x256 resolution icons made Vista world to feel like you have got a computer from heaven. Networking aspect has improved further in Windows Vista, with the introduction of further security enhancements. Performance wise, vista makes life better, when compared with its predecessors. Vista Disadvantages:1. Requirements high, too hot deal:Windows Vista, the next generation operating system requires superb computer to install. It consumes a lot more resources than its predecessor windows XP. For vista Aero to work, you need to invest something more than what you would have expected to invest before. The graphics card requirement is quite high. The graphics card must be of DirectX 10 supported. The required minimum graphics memory on the graphics card is 128 MB. For better performance, graphics memory must be of 256 MB. The minimum hard disk space required is 20 GB for installation of Windows Vista. Processor speed is also expected to be high for Aero to work smoothly without causing any hiccups. The memory requirement for Windows Vista system is high. The system will work smoothly when one has got RAM of about 2 GB installed. Totally, I would like to say that, Windows vista eats up lot of resources, than its predecessor, the Windows XP. 2. Regarding price, sucking your hard earned money:The price of Windows Vista Ultimate edition seems to be too high. Ordinary user cannot thus, have a look into all the features of Vista, which is only available in the Ultimate Edition. Microsoft seems to be not so interested in country wise markets. The prices are set according to the US market. However these prices are on higher side for developing Asian countries. Microsoft should set the price of Vista as per the market. It is the time for Microsoft to think over this aspect, having introduced stricter validation process. 3. Replace the oldies, another way of extracting:This is a usual problem, which always exists whenever new operating system gets released, and you have an old system or have some old components in the system. If one decides to install windows vista in the old system, then they should check the compatibility of system components, checking whether Vista supports them or not. Some manufacturers will still provide Vista support for the oldies by providing the latest drivers for the same. If manufacturers are not providing the latest drivers, you need to purchase a new device as a replacement for the existing device. Before, you purchase a new device you need to check out for Vista compatible or Vista ready logo, which is put up on the device. 4.Window appearance. Did you like the different look?In Windows Vista, the window appearance underwent lot of unwanted changes. The windows in Windows Vista, the window appears similar to that of MAC OSX. The Minimize, Maximize, and Close buttons, wore a different look. The three buttons got reduced in their sizes, making them unclear to aged people, people with eye sight problems. The minimize, maximize, and close buttons have reduced in sizes. The icon in the other end has disappeared, which makes the window slightly dull in appearance.

In overall, the new operating system, Windows Vista is said to be an ideal replacement to its predecessor, the Windows XP.

http://www.vistahunt.com/windows-vista-advantages-and-disadvantages.HTML