I have used Limewire 'free' for years and had no problems.
I now have the 'paid for' version - just because i am updating my extensive singles colection to digital, and some of the stuff is too rare to find on the 'free', but the 'paid for' has turned them up.
Having said that, I have ever downloaded any albums, only ever old singles, so I guess the chances of virus geeks bothering with the songs I want are slim.
Just be aware of any file that has a '117' measurement - it's always a really irritating lousy Bull Clinton ad. for a gadget store - save yourself the probelm and avoid them - because almost anything you put in will offer one to you as part of the listed choices.
As a final point, you should as a matter of course have good anti-spyware fitted, and run it regularly - just because if you surf the net at all, you are open to viruses, which can be serious. I got my hard drive frield by a Trojan two years ago, had to have it wiped and re-installed - that was not from LW either!
Be careful out there ...