Vista - 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 after searching the internet for 2 days i couldn't find a problem like mine.....
Ok, I have a HP desktop computer model no. m80575a with Windows Vista Home Premium x32. I downlaoded a program that contained an application 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 system tray saying that my video card had an error. I ignored it because I was in the middle of typing something; and i now i look back i was VERY stupid .

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

Unfortuanately my hoped dropped again after weird lines and Dollar 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 i ran Sytem recovery and it was successful, so i restarted the computer to reinstall everything. However, the lines and dollar signs were stil there when i rebooted, and after the vista splash screen and the 'please wait while the computer runs for the first time' message, the screen goes blank for 10 minutes and a Blue Screen of Death error message appears. I try using the 'run computer normally' option but same thing happens.

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

I think it is a virus because of the program that i downloaded, because it was not downloaded from the original site...
but it might be a registry problem because of the application that added the entry to registry...
Or it could be a video card problem (hardware or software problem, i dunno) because of the errror message before my computer crashed and 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 are still on and if they are damaged my i cannot claim my warranty. So i don't want to do anything that requires opening the computer case. The reason i havn't called in warranty is because my dad will kill me if i screwed up ths computer, so i just want to do as much as I can before he comes back from holidays.
I think it might be a virus that is preventing the video card from working? (is this even possible?) or the corrupt registry preventing me from logigng into login screen?

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

BTW, i finally caught a glimps of the blue screen error and it was:

"Attempt to reset the display driver and recover from timeout failed"

I am almost certain it is a video card problem. Please post what you guys think anyway. I was able to boot into Ultimate Boot Cd for Windows and after looking in device manager, Multimedia Controller, PCI Device and Video controller (VGA compatible) had errors and they all have something with the video card.