I'm pretty sure it will work, it will just most-likely just run at PC2700 speeds, but anything is possible. Do the best thing possible, go to www.crucial.com
and buy their RAM for your system. Uber fast shipping and lifetime warranty on RAM.
Dell Precision 670 (3.4GHz DP Xeon, 4GB DDR2, XPSP3)
Dell D800 (1.8GHz, 1GB, XPSP3)
I work with computers, I play FFXI.