I think a 64bit version will only make difference if all your comp parts support 64bits, ie a mobo like the one i have: asus p4W64ws, and processors like amd 64 or intel core2duo
IMO Антивирус Касперского (Kaspersky) is much better than avast, i had both and I can say that avast can miss a lot of trojans and worms, whoch it did some time ago when i had my comp infected, then I tried to scan with Kaspersky and voila! There were 125 infected files missed by avast.
BTW new versions of Kaspersky (v6 and v7) are a LOT faster and more bug-free than the older (v5)
Niko, you got pretty famous with your username, huh?
However you should know that if some friend/pal of yours calls you "n00b" that doesn't mean he wanted to insult you. if someone from outside calls you a noob, don't get mad, just prove them you ain't a noob, not by words, but by action (racing) if you want, if you're not into proving stuff, then just don't react and drive. If that insulting person will continue insulting, spamming, he'll possibly get kicked/banned pretty soon.