The Crucial Ballistix has tighter timings and so will have lower latencies. This translates to slightly faster RAM. They also have a lifetime warranty, which I personally have never had to use. I use Crucial RAM in nearly every system I build. I even use it in my mission critical servers at work due to their proven reliability. As for the Raptors...you may want to do some reading up on them. I have a pair of 36GB Raptors in my system and while they are fast I believe a pair of NCQ capable drives would outperform them. Raptors are also not native SATA drives...WD uses a PATA to SATA converter on the drive PCB.