As you may (or may not) be aware, there are several online virus checking services which will allow you to scan your entire hard drive without installing any software, however I have personally found that using a single file scanner is the most useful tool.

My personal favorite is Kaspersky’s single file scanner. Since I use AVG on my home computer, this online tool allow me to check anything I am highly suspicious of using an alternate scanner. If the file passes both scanner’s tests then I *assume* it is ok.

Usage is self explanitory, just browse to the file you want check and then submit it. It is then checked against the latest Kaspersky scanning engine and lets you know the results.