Np. Well... you should be able to open them like normal in safe mode. There is "Safe Mode with Networking" you can try that option, there should only be one option on what OS to choose after that. Technically you could download anything you need to in safe mode with this option. Just be careful you are running pretty bare to the net. Basically no protection.
Then you would want to select administrator (assuming windows XP here). Don't choose the system restore option in safe mode (click yes I think or whatever option doesn't do system restore). I don't remember what version of windows you have. I am just going to throw out there you press F8 (for most situations) every few seconds as your computer starts up to access the menu. It sounds like you already know but just giving some info in case. But yeah after you get into safe mode just go to the start menu and open Avast! up and get to scanning. It works just the same. The resident shields don't work and ZoneAlarm won't load because it uses a windows service. Safe mode is really limited so BE CAREFUL ON THE INTERNET! If you download stuff only go to trusted sites!
Other than that if you can't transfer any files over to the compromised machine from the working one VIA burning a CD or USB device. You are going to have to work with what you got. HOPEFULLY you can get a filename/virus type so you can go from there to remove it VIA safe mode. OR Avast! just removes it like magic
. The best thing to do is get all these tools you have been advised on this thread, transfer them to the compromised machine in safe mode and scan the computer like there is no tomorrow. You can try to download them in safe mode with networking just BE CAREFUL WHERE YOU GO! Hehe. It sounds like you can get into safe mode so there is still hope, not saying for definite though, to fix your machine. Good luck! Post if you have any other questions hopefully we can help.