I did this, and boy do I wish I would have added a second raid, or even single drive, for my OS. My computer becomes unusable when I thrash on the drives by unraring a large archive or something. I am going to toss in a mid-level SSD for the OS so I can avoid this hit.
Yeah I actually have 3x750gb right now for media storage and a 500gb drive for OS. I get a performance boost from the RAID, and don't have it impact my OS. Ideally I would toss in another 500gb and RAID for performance on my main drive, but I haven't gotten around to it yet. SSD would be nice, but 500gb HD for $60 is hard to beat.
