Hi Jay,
Here's some options I posted recently for someone else with similar questions. I think it may help you:
If you want the best possible speed for the lowest possible cost, then you might consider the following combinations.
The new Sonnet Tempo-X SATA card (4 internal + 4 external SATA ports). http://www.sonnettech.com/product/tempo-x_sata44.html
Plus:
You could add either 4 internal SATA drives by using the cost effective G5 Drive Bracket http://g5drivebracket.com/ or the more expensive, but more proven brackets from Trans Intl or ProMax http://www.transintl.com/store/category.cfm?Category=2490 (good solution for the money)
You could add 4 external SATA drives by purchasing enclosures for them (better solution).
You could add both internal and external SATA drives for an 8 drive RAID by using the Sonnet card (best solution).
These are all for someone that doesn't need any support to setup, install and run these do-it-yourself RAID's. If you need/want more support and a more proven solution while still keeping the cost fairly low I contact ProMax about one of their SATAMAXI systems. http://www.promax.com/Products/SubCat/Storage/Internal%20SATA
Now keep in mind, while these are relatively fast and cheap solutions. They have no redundancy and their speed drops considerably as the drives fill up. If you want a pro system with all the support, redundancy, relatively consistent speed and setup tools that many pro users would require… you'd need to move up to something like an Xserve or Huge Systems RAID.
You can find more info on some of the solutions here: http://barefeats.com/
Now, he was looking for four drives instead of two. You could start with two drives if you wanted. I usually recommend the Hitachi 250gb drives with the 8mb caches (There are hard drives with 16mb caches available now too). The Hitachi are cost effective, fast and usually reliable. Hitachi is the brand used by most of the current RAID manufacturers. Apple even uses them in the Xserve RAID. Barefeats.com can give you more info on how drives compare as well, so you may want to read up on it a little. I think moving to SATA and leaving your old SCSI machine behind is the way to go. Even a Firewire RAID like the G-RAID or LaCie Bigger Disk would be preferable:
http://www.medea.com/ http://www.store.yahoo.com/medeacorp/graid.html
200,000 clips is a lot. I can't imagine capturing that many. It seems like it would take years unless you had several people/systems working on it. Just logging that many clips would be a huge job. And its going to put some miles on the Beta decks. What exactly is the project? What/how are all these clips going to be used and why P-JPEG? Drives are cheap now.
If you're just going to back up all these clips to be used in different ways later. I suggest just capturing them uncompressed and buying lots of Firewire drives to keep them on. You're not going to want to render these clips to another codec if you don't have to.
I'm in the valley, maybe I could be of assistance on this project. I have a couple of well equipped FCP systems at my home office.
email me direct if you want to talk about it (click on my bio or my face above).
Tony!