The thing is, my computer, withing 15 seconds of logging in, says there is an error and it will shut down in 60 seconds, in all modes.
Oh, didn't notice that, sorry.
Don't give up, all hope is not gone. Download and burn yourself an
F-secure rescue CD and boot from it. There are many others, too, but this one can look foor rootkits. Unfortunately these Linux based things don't mix with all brands of networking cards. In that case insert another netcard with a commonly used chip like Realtek or 3com, preferably a little older one. I have found it easier than the USB updating system they offer. In fact, I once spent a good half an hour with their tech on the phone trying to get the USB update to work
.
After having cleaned your computer, try to boot. If the viruses have damaged something and your rebooting problems continue, boot again tapping F8 and choose "Repair your computer". In the command prompt, run "chkdsk /r" (without quotes). Hopefully your boot options haven't been corrupted by the virus, otherwise you'd only be given the opportunity to reinstall to factory defaults. In that case you should get a Vista repair disk to run the repair options.