I always heard reports that the p2p browsers inc. Ares were not really that good, compared to specialist stand alone browsers. Perhaps you are right re: old PCs but I'm not sure old PCs will deal that well with the latest Limewire versions. There is something that is related and will interest you, although this is the first and last I heard of it. There is talk of being able to operate Limewire from your browser ....possibly in the future:

http://www.limewire.org/blog/?p=192