Compatibility, wide-spread use, and video games. Other than that, Linux or apple are more stable and usually faster on the same hardware. (don't know about new apple o/s's though.
If you want the ability to play the latest games go with windows but I'd go with xp home or pro because vista is facing alot of problems and it would be best to avoid any headaches but if gaming is...
Different operating systems have differing features, though they all have the primary function of controlling the software and programs running on a computer or other device.
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