A friend of mine gave me a new 160gb WD Raptor(nice guy, eh

). I'm not sure what to do with it. I currently run a pair of WD Blacks in RAID 0 as my main partition with the OS, data and games, back-up to a 1Tb drive and downloads to a USB HD.
I'm not sure if the Raptor would do best as a dedicated OS drive or if I should just plunk it in as space for games?
What would you do with it...?