I finally got a power supply for my Supermicro Xeon mobo and got XP installed this evening. Hyper threading is pretty cool. There are two physical processors, but XP's task manager shows 4 processors. I started up Seti Driver and by default it wants to run 4 instances of the client, so it also thinks there are 4 processors. I haven't had time to benchmark it, but I did run Sandra. It has scores comparable to an older 8 cpu xeon system! This is looking like one fast box.