A decent reliable anti-virus software. Other security checkers such as anti-malware, anti-adware, anti-spyware. You do need to be careful of your choices because some commercial brands will give false-positives just to make you think they are doing something. Some free brands do better.

Although the post is very old, check Sleepless's post here http://www.gnutellaforums.com/gettin...ation-etc.html. Alternatively send Sleepless a message to inquire on the best ways these days.