Depends what your doing. If you by yourself and have a lot of money then go witha PC running Vista 64 bit. And get virtual box to cover everything else. Honestly I dont understand what people dont like about Vista. Its the best thing thats happened to me next to getting an android phone.
And if you’re playing with you friends and / or dont have that much money, Then a Xbox 360 or a PS3 is the best. Sometimes the graphics on a console can be much better than on the PC. Assasins creed is a good example. And as to the whole PS3 vs Xbox 360, The Xbox has better games and controls but the PS3 can beat the Xbox hardware wise.