If you want to keep your mac pure. Run fusion. Set up a Windows or better yet, an Umbutu VM and run it on that. If you run it as a restricted user, you should be ok.
But before polluting your vm with limewire, though, make a clone of it. so when it becomes infected, you just delete it and make another copy of the pristine clone.
Safe and easy.
VMs are a godsend. make use of them. With VM's you can have a "disposable" machine that you can recreate, in a Virginal state in 5 minutes.
While they're good in OSX, they're even better in windows. VMs can be used to combat the dreaded registry bloat. Want to try a new app, but am unsure it will uninstall properly or plunge you into dll hell, run it in a vm. Then throw away that vm when you are done.
Its so elegantly great, I'm . . . getting a bit excited. /