Why not return the 25GB unit for a replacement...it should still be under waranty, even if you bought it used....just call WD and say "I lost the receipt" or "it was a gift" It will be under warranty so long as the manufacture date is withing the standard warranty period....
For film editing, I would definetly recommend SCSI setup. Low CPU overhead, even if it isnt' the fastest. Use a IDE for storage, but SCSI to work from.
Do this. Warranty Replace the WD unit and make it primary HD. Buy a cheap 2940UW or equiv. SCSI Card and like a 10GB SCSI-2 drive. Use the SCSI drive for all temp, and in-work video files. When done, store it on the WD unit.
Transfer rates don't help if your CPU is busy trying to processes video and store/retreive data....
I did a setup like this couple years ago when 2GB was king....
My Two Pesos...