I have AMD 64 BIT, but in very true opinion, do not use 64-bit O/S until Vista, as by then, probably 80% of the softwares should have become 64-bit, as now if you use 32bit applications on 64-bit o/s, they'll tend to be slow compared to running on 32bit O/S. i as well went to buy a 64-bit as when i bought mine 4400+, but at the last minute keeping all things in mind, I cancelled my program. also, there miht be some hardware driver issues also on 64-bit O/S. so better wait for Vista. like I am doing.
Intel Core2Quad 2.66Ghz 12MB L2-Cache
4096MB DDR Kingston Hyper-X
XFX 9600GT AlphaDog
Seagate 2 X 320GB SATA2
LG L246WH Flatron 24"