Just one dumb question you say you did not download anything. If you did not download anything then how did you get the virus are you saying that it came in LimeWire. If so where did you get your version of LimeWire did you use a different P2P program like BearShare and download it from the Gnutella net. If you got LimeWire from the official site there is no way it came with a virus in it.
You can get LimeWire at the link below it is the official site. But you must use a little common since when downloading files from the net. Read some of the stickies on viruses and rules to follow when downloading from the net. There are allot of viruses out there so beware.
http://www.limewire.com/english/content/download.shtml