Hey all, it seems that my computer is infected with a virus. I repeatedly get the annoying "AntiVirus Software Alert" popup on my screen and wants me to install an antivirus program. I already have AVG anti-virus but it fails to open up

I followed the stickey about dealing with viruses/spyware/malaware. I downloaded the programs and tried running them in Safe Mode but they failed to open. For Ad-Aware it said I needed some sort of Visual C++ Programming installed, for spybot it said it wasn't connecting to the server, and for Hijack This it said that the windows installer can't run. What to do now?

Pleasee help, thank you!!