Basically your question ignores the fact that a Xbox 360 game does not play in a PC. The game versions must have compatibly to play each other and not merely the same title.
Yes, you can import and add non-steam games to your Steam library. From within the library you can launch and run any games, although 'Steam achievements' will only be available for Steam enabled games.
Windows Vista games are games that belong to Windows Vista, which can be accessed through their Windows Vista software. You can easily download free games onto your computer.
Most games written for Windows 3.1 or Windows 95 will run on Windows 98. Games that were only written with Windows 2000 or later in mind will usually not run on Windows 98.
some games
Games that are written specifically for Windows Vista will not work on Windows XP. Most games are written so that they will work on both.
Do you mean the games say "compatible with windows 98?" and you have Windows XP? Games are backwards compatible. Meaning, if the games say "windows 98", windows 95 is ok (anything before windows 98 will work). But it is not forward compatible--Windows 2000, windows xp, etc. will not work. does this answer?
Windows Games on Demand was created in 2009.
Yes. Windows Vista can run many games and applications that are available for download. You may wish to check to see if there are any known compatibility problems between your game and Windows Vista.
Yes. You can install and play games in Windows 7.
No it is not java enabled phone
Only games that worked in Windows Vista will work for Windows 7. Unless, they are games such as The Sims or SimCity.
Games written for Mac OS X will work on a Mac. Games written for the Windows operating system will require the Windows operating system to be installed on a Mac to work. Some Windows games can be used on a Mac without Windows by using CrossOver Games software.