Antivirus system pro

Hi,
I have an antivirus system pro on my comp which seems to have infected all my files such that I am unable to open anything. When I do click on my data/files in the comp it keeps showing the message "application cannot be executed. The file ______.exe is infected." It is also not letting me open internet explorer or firefox. Occasionally I am able to check my email but thats it. I am unable to download any program to get rid of this virus.
I am very concerned about losing my data, so please advise.

Thanks

Hello.
Since internet seems to be out of the question on the infected machine, you'll need another machine and transfer tools via CD or USB, or some other form of file transportation.