Aaron,
I have similar issues with doing video and multi track music editing. It is hell on the drive.
I few tips...
1) Keep your OS on a seperate dive / partition from your data.
Its best to have it on on a seperate drive...
I keep an 30gig drive on hand for OS and OS related shit.
Then applications go on a 100gig, then I have the data drives internal I have a 120, external I have 420 gigs of firewire/ide's
2) A fast firewire array for raw editing works wonders.
3) Dont buy shitty drives

10,000 rpm's, scsi is even better but I dont know many people who still use scsi unless there in a raid.
4) Common sense use highest ata settings you can, dont overclock your processor, make sure dma settings are correct
5) Dont run stock windows defrag, it does such a shitty job, I use O&O defrag, I also dont like norton as it adds so many components that seem to fire when you least expect it which is bad for audio work, not necessarly the case with video though.
By the way, the Cannon G3 came in yesterday...Fucking nice...I'm loving it