Recover from driver problem

Hi,
My first installation of XP seems to have a major driver incompatibility.
I was plagued by BSODs and it was getting very bad and so decided to make a
second Window installation on a second harddisk that I have on my PC. That
worked great and is very stable.
Since the PC HW is very stable when new I assume my asumption that it is
some SW driver that I have loaded (and I tend to try a lot of different SW
utilities).
My problem is that while I was doing the installation I managed to start a
partial reinstall on my old installation (don't ask me how, it seems that the
C and D drives swap names depending on which installation is active)!
Anyhow, now when I try to start up the old instalation I have to go
through the Windows Startup (using the CD-ROM) and I get a constant BSOD
during the process.
I found (and thought I had saved) a Microsoft article where it described
how to delete two files in C:\Windows which essentially makes the system
revert to a basic driver level. This would allow me to more cleanly access my
old data (emails, photos etc).
Any ideas? I have four userids on the old installation (me and my family)
and so would like to keep that information also.
thanks.