Although this is not the best place to be discussing potential legal liability, the liability that might come your way has nothing to do with Limewire per se. The potential liability is attracted by you offering a cache of copyright-protected music for sharing on Gnutella (or any of the other p2p systems for that matter). Self-evidently, the larger the cache you offer, the more likely it is to attract the attention of the monitoring "authorities". And, yes, there are ways of monitoring who attempts access to your computer but, again, this is not the forum on which to discuss it.