I had a computer's registry go bad on my recently, so what I chose to do was use an External Hard Drive Enclosure (you can also use a hotswap if you want) and used the Windows Repair file to restore the registry to the first time Windows opened.
It's not exactly ideal, but if the hard drive still posts you should be able to do it.
Before I give you the location of the file, I have a few warnings:
1. This is not the same as a system restore point. Using this method of registry repair can, and often does, cause many of your current hardware drivers to cease function. If you have components like video cards, video capture boards, modems, LAN adapters, etc. they will need to be reinstalled on the computer before they're operational.
2. If the issue is related to the SOFTWARE registry tree, using the SOFTWARE registry file to repair will remove the registry entries for your Add/Remove programs list, so you will probably need to reinstall nearly all of the software on the computer, because these registry entries are often used to help update your software, rather than scanning your computer for the location of your files.
3. If there is any possibility that the errors are a result of another component in your computer, this can hide the actual problem amidst a plethora of other needs.
The file containing the original registry entries for the first time you opened windows is found here:
'C':\WINDOWS\repair
C is replaced, as normal, with whatever drive your OS is on. Please note that, since you're doing this repair by connecting the hard drive from your damaged computer to another computer, the OS you're doing this to is NOT the one you're operating. Making this repair on an otherwise functional computer is far from ideal.
The location that these files should be
copied (not simply moved) to is
'C':\WINDOWS\system32\config
I don't recommend moving the file named "software" because, as I said above, this may require you to reinstall everything.
For more information and other details:
http://support.microsoft.com/kb/307545
This will not wipe your secondary storage, so all of your documents and such will still be intact. In fact, even if you move the software registry file, the program installs will still exist on the hard drive. It can be quite tedious to manually remove these issues, and, if at all possible, try to use the Windows Recovery console on the disks that came with your computer or your Windows OS disk. Ideally, you would use this method to fetch your data and then format the drive along with a fresh OS reinstall, but it seemed like that might have been out of the question for you.