I am using my ISP's anti virus program. However after running the antivirus program for over 2 hours it had only check 25% of my hard drive. My hard drive is about 150 Gig and 118 of it is free. So I contacted them (Bell Sympatico) and they suggested that I remove the program and then reinstall it which I did. However there was a problem with the installation and i had to get on the phone with them, where I stayed for over an hour until it was fixed. But it is still running as slow as ever.
So my question is this. Even though they informed me that I cannot run 2 antivirus programs, I have been told that I can. As long as both are not running at the same time. So can i run a second program in the background and only turn it on when I want to run an antivirus check. And if so, can anyone suggest one fo the free antivirus programs to download? Since i am relatively new at doing these things, I hope that I have explained this properly.
Thanks for any help that I might get.

Hello,running two can some times cause conflicts.If this supplied ons is causing problems uninstall it and download this one:AVG Anti-Virus Free Edition - Free software downloads and reviews - CNET Download.com

Will it cause problems if it is NOT running, but I use it to check for viruses periodically?

Yes it will - when you want to check for viruses with the new antivirus you will need to disable your current antivirus, then scan, then disable new antivirus and reenable old. It's far easier to have just one antivirus that works and scans properly.

thanks guys