Had some problems from shared files with some Trojan Horses embedded.

Fellow tech turned me on to "The Cleaner" from Moosoft dot com

http://www.moosoft.com

Was impressed enough with it after trial time to purchace its use.
(I have NO financial interest in Moosoft, other than happy customer of products)

All my files get blasted with it and Grisoft's AVG daily to ensure that my box and files shared are clean of ALL bugs.

Will say with Limewire compared to the other services virusii and Trojans seem to be less of a problem.