You have a good system by the looks of it.
I'm not an expert or anything.. The latest CPU's are dual-core and quad-core.
http://en.wikipedia.org/wiki/Multi-core_(computing)
I just bought a system which has 2GB RAM, however it is "Corsair® 2GB DDR2 XMS2" compared to your RDRAM. I think RDRAM is outdated.
That's all I know really.