Most of us here run Athlon 64, some are switching over to 64 x2 dual cores, like me. Most of us also just run XP Pro, no need for XP 64. My Athlon 3800+ X2 runs perfectly fine with XP Pro, you just got to make sure you load the proper drivers correctly. Until i hear about how XP 64 is a 1000% improvement, I'm sticking with good old XP Pro. As for 4 monitors on 1 PC? That seems overkill to me, never seen such a setup before. I have dual 19"s flat panels, and it's great.