Is there a way to repair infected programs by virus/worms manually?

My computer is devastated with viruses. Almost my .exe files are infected. I tried to scan it using a free version of the Avast virus scanner but it seems that the repair option doesn't work.
If I try to delete the infected files then things would get bad. M installed programs won't work. I do have an option of reformatting my computer but that would be the last option but if only I could repair the .exe files manually then that would be a better option. By the way the virus is win32/Salit. I don't have an Idea about this virus or where I got it from.
After I scanned my computer I've got 146 files which are infected, bad isn't it? Is there anyone who knows how to repair it manually or if there any software that may help me with my problem? Also if there are anyway of solving my problem please provide me on how to. I'm looking forward for your answer, I really want my computer to be virus free.
