I have two Dell Precision 650 workstations that have a dual 2.66 Xeon processor setup. I purchased some compatible memory from Fry’s but it caused both computers to have periodic system lockups. So, I went ahead and removed the Fry’s memory, purchased the expensive Dell memory, and installed the new memory into both computers. The Dell memory worked! FWIW they both have 1.50 GB of RAM.
Since your luck is better than mine, you may just get by with some cheaper memory. Damn, KJ you have the best luck!