Got a hell of a deal on this Dimension 9150. Pentium D 521 Prescott (2.8Ghz) 512 MB DDR2 PC4300 128 MB ATI Radeon X300SE CDRW/DVD Combo Drive DVD-ROM Drive Onboard sound Definitely getting a new video card, but its not on the top of the list at the moment. What is close to the top is some more RAM for this machine. Have been considering upgrading to 2GB. I plan on replacing what is already in there, not adding to it. Do I need to get PC4300 or would the PC5400 work too? What difference would it make? What does the Cas Latency do?