I personally use AVG. On the side note, I know you said free anti-viruses, but anyone that still uses paid Norton Antivirus and McAfee...is a noob.
If you got a nasty infection Malewarebytes is the best free removal tool but not the best realtime protector.
So I can download Malwarebytes after the fact and it will remove the virus (hopefully)? I can still access the Internet from the other infected computer..
Yes depending on the infection. Some are damn nasty and disable everything by hitting your registry. If you can't access the Internet, download from another machine. If the virus appears to be winning, shut down and use a dual boot CD such as Ultimate Boot CD that will allow you access to your file but loads a Linux OS or Windows OS in place of your infected OS. Whatever virus is running on your machine won't be activated and you can then remove it or at least recover your files without spreading the infection.
welp, that didn't work. I couldn't get Malwarebytes to open and run. I am going to assume the virus prevented me from doing that. Does that mean that this infection is pretty nasty or is that typical of programs not working when a computer is infected?