Hi all, thanks to anyone in advance for reading this and helping out.

EDIT: This problem was solved. Read my post below for the current problem I'm having.

I have Windows XP Professional, updated fully through SP3 from Microsoft, and yesterday got myself a copy of Vista Ultimate (Upgrade). I ran the upgrade advisor, and had a few software incompatibilities, so I uninstalled all of the problem programs except my video card driver and a DVD burning program (the upgrade manager said this was OK). Upgrade advisor gave me the green light, so I went ahead and started the upgrade. The problem arises during the final stage of the installation, "completing upgrade." At around 59% in that stage, the system reboots, but I get an error message, saying the installation cannot continue, because the file \Windows\System 32\dpkmhcpy.dat is corrupt. The first thing I did was roll back my installation to XP and uninstall the DVD program, then re-ran the upgrade. Same result. It suggested I boot from the CD and click "Repair my computer," which I did, but nothing happens. I let it "search for problems" for 8 hours while I slept and went to work. Nothing happened or got fixed. On my lunchbreak, I went home and downloaded, burned, and booted from the Vista Recovery CD, and did the Repair option there too. Still no luck.

When I get home from work I will be pulling out every piece of non-essential hardware and replacing my DVD drive with another one, maybe that will help. In the mean time, if anyone knows about my problem, I would love to hear from you I would LOVE to not have to wipe my drives and avoid doing a full clean install. dpkmhcpy.dat seems to be the only thing in my way, is there any way to replace that file via the command prompt? What does that file even do?

Also, on the Microsoft website, it says I can request assistance, but I need a product ID key. Where do I find that without actually being able to use Vista?

Computer specs:
C2D E6600, 2GB (2x1GB) Corsair XMS2 DDR2-800, eVGA GeForce 9800 GTX, Asus P5N32-SLI SE Deluxe, some Sony DVD drive (Optiarc or something), LG Blu-Ray/HD-DVD/DVD/CD combo drive, 2x 250GB HDDs, 1x 500GB HDD

The product ID key is your licence key and should be printed on the box...

Ah, THAT product ID... /slap forehead... I thought it was something else, since microsoft.com says to locate it, look in some file or something.

Anyways... an update to my situation:

After a few fruitless hours with Tech Support, I decided to try a few new routes. First, after research indicated it was safe to do so, I deleted 2 driver files for SCSI devices, of which I have none. That driver had been popping up as a problem which needed to be fixed before installing Vista, and 4 tries of disabling and uninstalling it via the Hardware Manager did nothing. I'm happy to say, deleting it didnt break anything.

Next I tackled dpkmhcpy.dat. I got to wondering, why does it seem like I'm the only person on the whole internet with this problem? Maybe I'm the only one with this file?? I looked at the other 2 computers in my house which run XP, and \Windows\System32\Drivers\dpkmhcpy.dat doesnt exist on any of them. Then I looked at the file itself and noted that it was created a few months ago, and there were no other files on my system that were created at the same time. I thought Hmmm.... maybe I can delete it? Since my access to the file was denied in both normal and safe modes, I booted from the XP disk into the recovery environment and renamed the file to dpkmhcpy_NEW.dat, and rebooted.... nothing was broken!! Yayy!! I wanted to be absolutely sure, so I then went back to the recovery environment, renamed the file to DONOTDELETE, and moved it from the drivers folder to C:. Still nothing broken! Lastly I transferred the file from my desktop to my laptop, and deleted it entirely from the desktop. Still working!! Success.

So now that the file is gone, I ran the Upgrade installer again. It was 5am, so I wished it Godspeed, said a prayer, and went to bed.

When I woke, it was BSoD

I ran the Startup Repair program after booting off the Vista disk and clicking Repair My Computer. Heres what I got:

Startup Repair cannot repair this computer automatically.

Problem signature:
Problem event name: StartupRepairV2
Problem Signature 01: ExternalMedia
Problem Signature 02: 6.0.6000.16386.6.0.6000.16386
Problem Signature 03: 6
Problem Signature 04: 131074
Problem Signature 05: FailureDuringSetup
Problem Signature 06: FailureDuringSetup
Problem Signature 07: 0
Problem Signature 08: 0
Problem Signature 09: unknown
Problem Signature 10: 1168
OS Version: 6.0.6000.2.0.0.256.1
Locale ID: 1033

So... what does one do when one's Vista BSoD's on the install?? Call more tech support?

Back up your data and do a clean install of Vista. Upgrades have ALWAYS been an issue with Windows... even as far back as Windows 3.1 and Windows 95. You're much better off installing clean and then restoring your data.