The DDR2 Sounds good, why sell your current graphics though?! I've heard PCI express is crappy. I didn't know prescotts used different motherboards, are you sure they do?
**EDIT** Just stick your 5900 in that machine to sell and keep your xfx 6800, or have you sold it to LK already?
Asus A7N8X Deluxe - Rev 2.0 - Bios Ver. 1007
AMD Athlon XP-M 2200+ - @ 11x188 = 2Ghz (1.75Vcore)
ATi Radeon 9700 Pro (Almost as good as my old 5950U!)
Corsair 512MB XMS TwinX Low Latency DDR 400 - @ 188Mhz
3dmark03 Score: 5086