Yes, you can. But sadly a lot of software designed for older windows versions will not work under windows 7. You can use Virtual PC if you want run something working under XP but on windows 7 computer.
Windows 8 does have the ability to launch applications in compatibility modes which support older Windows versions.
There are many versions of Windows available for laptops today. Most laptops run on the latest versions of Windows (currently Windows 8). Many laptops also run on Windows 7.
Windows Vista
There are several emulators to run other systems software on Windows, but there is nothing decent (as in working reliably with any software) for running Mac OS X software on Windows.
World of Warcraft should run on all versions of Windows. Note on most versions of Windows, you will need to run it in administrative mode.
Yes, a lot of the OS is built on the same code and same software may be found on the W8. Most software running on W7 may run on W8, and you can also run programs in compability mode for older operating systems.
Windows Virtual PC enables a PC user with a more recent version of Windows, (such as Windows 7), to run an older version of Windows (such as Windows XP). Windows Virtual PC can run right from the desktop and only for specific programs. Virtual PC was designed to eliminate compatibility issues with older software on newer Windows operating systems.
Any amount will be fine in Windows and Mac. However, with lower amounts of RAM, you may need to run older versions of Opera.
as far as i know yes if you have a computer able to run it (odds are yes) and the install disk and stuff
Klik and play does run on windows 7 but only on the 32bit versions it will not run on windows 7 64bit
depends on the software many games must have the older software. Windows 95 games don't all run on windows XP let alone windows vista or windows 7
I think your best bet is to partition your hard drive and run two operating systems. I think the platform of both operating systems are different. some older programs use MS-DOS which can run in windows 98 but wont run in XP and higher versions of windows. there are also emulator programs you can use to run older programs. As for running 98 in a windows 7 environment I don't believe that is possible.