I'm building a new one, which will be similar to the one in my signature. This time, however, I plan to use two 150GB WD Raptors in RAID 0 (ports SATA3 & SATA4) for data, and one dedicated Raptor (in red port SATA1) for the OS. My question is what size Raptor would you suggest for the OS? Would 74GB be too large? Is partitioning recommended?