PIII faster than a Dual core processor????

I ran AVG virus scan on my PIII thinkpad laptop with 586MB RAM, and on my Dell optiplex desktop with duo core processor (2.8ghz) and 2GB RAM. I started the scan on the desktop first, and then the laptop. The laptop had scanned more files in a shorter period of time!!!!! How is this possible????confused

 

The size, read/write speed of hard drives, number of files to be inspected, type/amount of data on each hard drive, etc, etc...

This post probably would be better served in the software section though.