I'm the guy that has had all the problems with the 200GB WesternDigital HD. I took your advice and upgraded all the bios and drivers that I could find for my Gigabyte motherboard and the Promise ATA/Raid card, reloaded Windows XP and had gotten through a day without any problems. On the second day it hung somehow, I wasn't stressing it I thought, but I was playing a java crossword puzzle on line when it froze. I waited for a couple of minutes for it to recover, but when it didn't, I hit the master power switch!
Upon beginning to reboot it wouldn't and it was unable to boot to any of the recovery points that I also tried. When trying to boot to safe mode, it hung at C:Windows\System32\Drivers\mup.sys. I tried the "Fix" on the XP CD and got nowhere.
My solution has been to run Windows 98SE on a 27GB Maxtor HD and slaved the 200GB WesternDigital HD. A poor solution, I know, but even when I get a BSOD or it hangs, at least I can recover without having the whole OS becoming corrupted.