Since the nexus forums are down, I can't find another guide to fully clean install Oblivion. There was a step about deleting oblivion from the register. Could someone tell me what i should do there?
Edit the registry; find and delete the keys
HKEY_LOCAL_MACHINE\SOFTWARE\Bethesda Softworks\Oblivion
HKEY_LOCAL_MACHINE\SOFTWARE\Bethesda Softworks\Oblivion - Construction Set
and everything under them, if they're present.
On 32-bit Windows, the program you want to run is called "regedit". Just type regedit in the Run box on XP or the Search box on Vista or W7.
It's more complicated on 64-bit Windows, because the 32-bit registry is a hidden registry that needs a special version of regedit to access it. The incantation is
%systemroot%\syswow64\regedit
As before, you type the command (exactly as given) into the Run box or Search box.