The Best Windows OS made by Microsoft PERIOD no questions asked. If you have either XP or Vista pre-order or buy Windows 7 the day it releases.

I have the Final Windows 7 RTM Build and there are absolutely no bugs or errors, glitches, nothing. Unlike Vista, 7 is alot faster, stable, and easier to use than Vista. It boots up faster, general performance is faster. Its so good that it even rivals Windows XP in certain tasks.