my UDMA PC:

CPU: Duo CORE 2 QUAD Q6600 2.4GHz * 4 2M * 4
motherboards: MSI P45 Neo3 FR (support 8 SATA RAID0, 1,5)
Memory: Kingston DDR2 800 2G * 2 (motherboard with a dual-channel)
hard drive: HITACHI 500G SATA 16M
cards: 8600 GT
Power: 550 W server power
chassis: IPC chassis as the suspense with genuine 32 bitXP systems, to identify only 3 G memory. . . . . . . All have to know to install 64 bitXP

but I do not know whether or not to support UDMA 64big system

who can tell me？

I don't know for sure, but I'd strongly suspect using Windows XP 64-bit will open you up to all kinds of bugs. I tried it for a while, hoping to get a wonderful speed boost. After a month I realized the crashes and incompatibilities were not worth it. Perhaps it might be good for specific 64 bit applications (CAD, Audio/Video editing), but I doubt DR is a 64-bit-friendly field.