If you have a permanent internet connection and suspect an infection you may goto
http://www.dshield.org/ and click on
here (Are you cracked? Click here to see.) a data base will be searched to see if your IP is listed as an attacker.
If it is do something about. if is not listed means only lack of evidence.
I report in excess 1000 attacks on my IP every day to dshield and at times 1000+ per hour.