Vista won't boot into login? virus, video card or hardware problem?

Hi, I would like to say sorry in advance to this long post, but afte
searching the internet for 2 days i couldn't find a problem lik
mine....
Ok, I have a HP desktop computer model no. m80575a with Windows Vist
Home Premium x32. I downlaoded a program that contained an applicatio
that adds an entry into the registry in order for the program to work.
After installing, around 5 mins later an error poped up from the syste
tray saying that my video card had an error. I ignored it because I wa
in the middle of typing something; and i now i look back i was VER
stupid :cry:.

Anyway, I used the computer for a few more minutes before the it froz
and I had to manually shutdown the computer by holding down the O
button. The computer booted up fine and i used it again for a fe
minutes before it froze again. I manually shutdown the computer again b
pressing down the ON button, but this time it didn't boot up... After
few tries I replaced the DVI cable connected to the monitor with a VG
cable, and to my suprise the computer booted up this time

Unfortuanately my hoped dropped again after weird lines and Dolla
signs $ appeared in the BIOS. I pressed F8 and did a System reapir
which failed because it could not 'automatically repair computer'
However, the check for hardware errors found no hardware problems; so
ran Sytem recovery and it was successful, so i restarted the computer t
reinstall everything. However, the lines and dollar signs were sti
there when i rebooted, and after the vista splash screen and the 'pleas
wait while the computer runs for the first time' message, the scree
goes blank for 10 minutes and a Blue Screen of Death error messag
appears. I try using the 'run computer normally' option but same thin
happens.

Unfortuanately, because I have already run system recovery i cannot us
system restore because the points have already been erased. I canno
access Safemode either because windows is not installed
What can I do? my guess to this problem is either a virus, corrup
registry, or video card problem

I think it is a virus because of the program that i downloaded, becaus
it was not downloaded from the original site..
but it might be a registry problem because of the application tha
added the entry to registry..
Or it could be a video card problem (hardware or software problem,
dunno) because of the errror message before my computer crashed an
because the computer stops booting when it starts to use high graphics

I have heard that reseating the video card will help, but the seals ar
still on and if they are damaged my i cannot claim my warranty. So
don't want to do anything that requires opening the computer case. Th
reason i havn't called in warranty is because my dad will kill me if
screwed up ths computer, so i just want to do as much as I can before h
comes back from holidays
I think it might be a virus that is preventing the video card fro
working? (is this even possible?) or the corrupt registry preventing m
from logigng into login screen

Does anyone know what i should do? Is there a way to run window
normally in low graphics so i can know if it is a graph card problem o
not? What can i do to fix this problem?
Thanks in advance

--
chand