I downloaded the diagnostic and moade a bottable floppy. Put it in, turned on the machine, it started to load up and showed copyright info on the screen, then said "Critical Error: Aort, Retry, Ignore, Fail?" I had it retry a couple times, then let it fail, and it said "CauseWay error 11: DOS reported an error or corrupt file found." after which it shows the A:\> command prompt. I tried running the dlgdiag5.exe file from the disk at the command prompt then, but it just did the same thing.
Edit: I formatted the disk again, and it ran. I ran the diagnotic, and it said it didn't find any problems. I told it to zero-fill the drive, and it comes up and says are you sure and I said yes and then it said that there was a cable error. So I open up the case to verify that everything is connected properly, which it is. I turn the PS back on and turn the machine back on, and now the display won't even initialize.... grr. I'm going to go to bed and mess with it again tomorrow perhaps.
Edit2: just as I went to put the cover back on, a screw fell to the bottom of the case. I wasn't sure what it came from, but I noticed that when I put my hand on the VC heatsink (I have a zalman heatpipe on it) it wobbled. I took the VC out and saw that a screw was missing from the heatsink and that it wasn't making very good contact with the GPU. I put the screw back on, drew a deep breath and sighed when the display initialized. A fried graphics card was the last thing I needed.
Anyway, It seems like maybe things have been jostled around too much. I think that tomorrow I will take out all the cables, check to make sure that all of the hardware is mounted correctly and then put the cables back. I'll run the diagnotic again, and hopefully everything will work. If not... well.... bah.
Edit3: I kept getting that cable error, so I fiddled around with things. I tried using a different SATA cable, changing the SATA slot that I was plugged into, tried alternating between molex and SATA power conenctors, and nothing worked. I decided maybe I should try the other SATA controller on my board, even though it is primarily intended for RAID configuratins. I enabled the Promise SATA controller and set it to run in IDE mode, then ran diagnostics again. The check ran just fine, and now it's writing zeros to the drive. Hopefully I will be back up and running shortly. Thanks for the tip about the WD Data Lifeguard Tools. I didn't know about them, as this is my first WD drive.