LW Pro (like basic) has no bundled software (no extras, no malware). But LW can't control what's being shared on the Gnutella network...no Gnutella client can control that.

You have to be careful when downloading. Check file sizes, stay away from the obvious fakes (100 sources, 99 sources etc), avoid exe, zip & rar files.
Add words to your keyword filter to filter out the spam

Have a read through these for starters

Fake files showing up in search results
How to find music
WARNING: Viruses on the network you should be aware of
Direct instructions to eliminate porn from results