price comparison

Hey you guys! I really haven't got any idea if im in the good sub-furom but Let's post it here: What is the difference between home premium and professional in windows 7 because I noticed the difference in price.. What is better if you are buying your pc as a "gaming pc" to play games...

well i thought i knew everything but i guess not. i've got almost all of my computer picked out and now i'm looking at operating systems. i was on newegg and i see there's the 32 bit windows vista and the 64 bit windows vista. what's the difference? i also see dramatic price differences...