they have not gotten viruses FROM limewire, they downloaded virus from the network and ran them. thats why you should always use a good virus scanner like AVG or AVAST

both of which are free. also, never run .exe programs unless you have to, in which case you should ALWAYS scan executable files with an AV program before running them. this also applies to any executables and archives such as zip files.

the only 'safe' files you can be sure that wont have a virus are codec required video/audio... but wma/wmv filetypes are exceptions to this list. (blame the guys at microshit for creating this DRM loophole in their proprietary software and formats.) you can filter these filetypes out using the keyword filter and adding .wma and .wmv to the list. this also will help you reduce the number of spam results you see.

need me to explain anything else? LW itself contains absolutely no malware/viruses/trojans/spyware or adware. the source to LW is available for free at WWW.LimeWire.ORG .. so you can check this if you want. (you would just have to go through the tons of code) but hey, thats peace of mind i guess for some people.