This weekend I managed to get my hands on an Opteron system which was running the latest board from ASUS - the SK8n. However this board is slightly different to the ones which you have seen in reviews I played with version 1.0.3. With an Opteron 144 in it running at stock speed, with 1GB of Ram (2*512s). All of this was with a normal Maxtor 7200 ATA hard drive, and a NVIDIA FX5900 Ultra. We were running a non 64 bit version of Windows XP Pro.
The numbers were very impressive, I have not seen anything as fast at stock speed, and it looks like AMD have some very impressive 32bit 'emulation'.