RDRAM is far from garbage. It performs rather well and the only reason it isn't more widely used is it's $$. My Dell that I just disassembled to sell the parts used RDRAM. I only had 256mb of it but I could easly play games and run software that had a minimum requirement of 512mb of ram. Plus DDR performs better for gamers and is rather inexpensive.
If I remember right it was gonna cost me like $250+ to get 512mb of it when I wonted to upgrade it like a year ago. That might be why you don't see much of it. Lol !