download CPU-Z from www.cpuid.com
and it can tell you what RAM you have but honestly, 1gb of ValueRAM will be sufficient unless you want to overclock.
Then I'd suggest
OCZ Platinum Rev2
all those are $200+ but will overclock like mad.
What is your current PSU? What brand is it, how many watts and what is your +12v rated at in amps? (will say it on the side of the PSU on a sticker)
The best OC'ing mobo out there is the MSI Neo2 Platinum
BUT.........DFI which is basically the best OC'ing board out there will be releasing an nforce3 board with AGP here at the end of may possibly, so if you want to wait that long, that board will be way better than the MSI but currently the MSI Neo2 Plat is the best OC'ing board....yes better than the ABit although ABit is a good OC'ing board too.
That PSU looks cheap as hell catbert.
Personally I'd suggest something by thermaltake. Their purepower 480 and 560w PSU's are wonderful