There is an online virus checker available which not only scans your computer for viuses, it also has an online database of viruses and ways to remove them.

This is a free service, and it doesn't prevent viruses. I use it every couple weeks as a precaution, more or less due to the amount of time i work online.

It's from a company called Trend Micro, and their virus checker is called housecall.

Its website is housecall

Steve