Microsoft Windows XP Home Edition w/SP2 —
Well, if you have to use a PC, this would be a good operating system, I actually prefer Windows 2000 (it's got all the power of xp without all the hassles and performance bog-downs). Overall XP is pretty solid, it has good hardware driver auto-detection and still follows the Microsoft user interface that we are all used to. Vista seems to have strayed from this formula in order to compete with Apple (as if they could). If you haven't bought your computer already, buy an iMac, if you have a PC and need an OS or OS Upgrade, this would be as dependable as you could get... for the moment.