I'm satisfied with Grisoft's AVG, the antivirus program I use.
But ever so often, I'll do a spot check, especially if I spot a file that looks suspicious. (What's the phrase? Trust, but verify?)
I found two sites that will take your file and scan it very (and I mean very) thoroughly.
Virustotal runs the file by 29 antivirus programs, all in about two minutes. Jotti's Malware Scan is a little faster, but only has 15 programs available for scanning.
Either way, give them both a shot and let me know what you think.
Virustotal examines your file with 29 antivirus programs
