Hehe. That is the CPU I acutally upgraded from. I have a 2.2ghz Athlon 64 venice core on my computer and its socket 939, and I got a HUGE performance boost from the AMD Sempron 3000+.
Newegg.com is our friend. :-D :-)
Honeslty, id drop the socket 754 board and get a socket 939 w/ cpu for $112. Best money I spent so far. :-)