Mine's listed as 37MB/s. Is that enough headroom for 20MB/s Cineform?

For single track yes, but things get dicey if you have multiple tracks that all come from the same disk. Maybe 2 tracks will barely get by, but three or more tracks is not really enough.

That should work, so long as the drive is defragged.

It's a dedicated drive that only is used during capture and editing, it should work then. Once this one's full, I'll get another 32MB cache one with a fast response time (The ST3500320AS) and I'll re-install the current dedicated drive into it's original external casing (yes, I took a Lacie out of it's case, it's basically a ST3500830AS in a case linked through USB 2.0).

sriped barracude ES series drives.....you pay more for them but they are made to work in an enterprise environment with 24/7 reliability

Question about a noise coming from my PC. It is a brand new HP and I installed two new Seagate 500GB drives in RAID0. When the PC starts up and sometimes during usage, there is a high pitch whistle coming from it. I am almost sure it is the drive/s as it started right after I put them in. Is this normal or should I return the drives? Thanks.

Drives are out and no noise. Question, for just editing HDV is a RAID really needed and would the extra performance even be noticed?

Definitely, unless your editing is single track only.