about 3gb of ram is recommended for windows 7 starter.
To run windows 7 you need at least 4gb of ram
The least you need is 64M of ram but the recommended is 512M
Depending on which version of Windows, or Mac you use it can be between 1 and 2 GB of RAM needed For Windows 7 it is usually 1 GB of RAM, and if you use Mac then you will need 2 GB
You can run Windows 7 with 1-2 GB of RAM depending on what you are doing. (More stuff you need more RAM) I Would go with at least 4 if not 8 GB of RAM to run Windows 7.
Windows XP does not have the RAM, its the computer that has it. The amount of RAM can differ for each computer.
Windows seven home basic, or more commonly known as windows 7 starter is mainly used for netbooks that don't have very much RAM and hard drive space, and alos maybe not as much processing power. If you have a notebook laptop or a desktop PC consider Windows 7 Home Premium. Windows 7 starter lacks some features that home premium has like windows aero's transparency to save RAM and hard drive space for lower end computers.
Windows 7 Starter is only available for a 32-bit system, with the maximum RAM at 2 GB. Windows 7 Ultimate for a 32-bit system has a maximum RAM of 4 GB. Two more gigabytes are required. And if one gigabyte is equal to 1024 megabytes, then two are equal to 2048 MB. In short, the requirement is 2048 MB to upgrade from Starter to Ultimate.
it's the same as windows 2000 pro system requirements.
Windows XP can never "run like Windows 7", regardless of the amount of RAM installed.
It won't slow down your notebook as long as you have 1 GB of RAM on your notebook.
Any amount will be fine in Windows and Mac. However, with lower amounts of RAM, you may need to run older versions of Opera.
I'm not sure I fully understand your question but I will do my best to answer. You have a 3ghz processor with 1GB of ram. 512mb of ram is enough to run windows XP.