Sorry if I go off the point a little

PREAMBLE
I used my Abit GF4 Ti 4200 quite happily on XP for about 9 months,
then I downloaded an updated driver from www.abit.com.tw, I got a
message saying it hadn't got a windows logo certificate but I
installed it anyway.
Then when I boot(sequence goes VGA/Mboard/SCSI) random characters
appear all over boot screens.
Shortly afterwards, Windows refused to boot (and I wasn't able to
repair it cos i'd forgotten the admin password (stupid of me, i
know)).
So I buy a new IDE drive (cos I need to keep data on SCSI drives,
which I used to boot from) but now I cant load any drivers for my
graphics card

THE PROBLEM
I load the drivers and after rebooting my display is corrupted, I have
tried several versions; original CD, 2 versions from ABIT website,
generic driver from NVidia site. I also flashed my motherboard BIOS
because I read that might help. No luck (but now no random characters
on motherboard bootup screeen). I uninstall the drivers in safe mode
and am left with a very basic display that is readable and stable (so
card is not completely FUBAR)
I don't think the problem is related to Windows because I have dual
boot with 2 copies of XP on seperate partitions, both recently
installed and one of them in virgin state (only service packed) and
problem oocurs on both installs.

Is the VGA BIOS corrupted, is that possible?

MY SYSTEM
MSI 648 Max (SIS 648) socket 478
P4 1.8 willamette
768 Meg PC 2100
Abit GF$ Ti4200
Adaptec SCSI card AHA2940 (originally used to boot from)
2 x IBM 9.4 gig HDD
Cheetah 10 Gig IDE HDD (currently booting from this drive)