newbie can't restore OS because of virus(es)

[fuscorayj]

Hey all!<
My computer is self destructing, I did not renew my subscription to RegCure and everything has been going south since. I am no longer even able to log in without gettign a blue screen. I know I am loaded with viruses. I was in the middle of a VirusScan re-install with McAfee when I lost internet access. Now it's to the point that I can no longer log on. When I try to do an OS repair/ restore using manufacture's disk I get error messages that certain files do not pass the windows logo test, i say to copy anyway but then install does not finalize. I don't know where to start, I don't necessarily want to reformat the whole drive. Can anyone guide me in what steps to take using dos commands? I do not have anti virus software installed and do not have internet access. all I have is a DOS prompt
I am running XP home.
(this is not the infected computer)
Thanks,
Ray

[fuscorayj]

Thanks for all your help, I did the recommended reinstall  but w/out formatting, reinstalled McAfee virus scan plus, and have been updating and rescanning for 2 days straight and finally have a "Clean" scan log! yea!!!  , I was able to boot in safe mode and change ownership of all my old password protected folders too! Thanks for all your help!!!
Ray