Yes well, i was overdoing it a bit, allthough it's easy to spend that amount on a raid.

Depending on the frame rate and resolution, you need write speeds of at least 120MB/s and as high as 180MB/s.
Why not just use Ultra320 SCSI arrays -- aren't they faster? They are historically faster, but are expensive and the drive capacity is one-third that of most contemporary SATA and PATA drives.
http://www.barefeats.com/hard46.html provides an interesting speedtest.