In my newest PC (=my game machine :-)) I used 2x Corsair 256Mb DDR PC2700 CAS2 Low Latency. Works very well! :-) It's built on the Abit NF7-S rev 2.0 motherboard (with the nForce2 chipset).
In my Pegasos I use 1x 512MB registered Samsung module. Works very well too! :-)