There is no need to return the Raptor. A Raptor HD is the best choice for a system drive. Contrary to what that guy was saying how Raptors are only useful transferring large files, this is false! Raptors shine with their low average seek times. This means faster Windows load, faster game level load, etc. Faster searching, installing, etc.
Anyway, pick up a WD6400AAKS as a solid 7200rpm drive. Don't bother with Seagate. Their 7200.11 drives underperform compared to the competition right now. Don't bother with Samsung either - sure their F1 line is fast but Samsung is not a big name in hard drives yet so I wouldn't pay big money for this. It's like buying a Hyundai Sonata over a Toyota Camry. Sure, the Hyundai works just like the Camry, but it's a Hyundai for chrissake!