Try downloading the latest Java client from sun microsystems 1.4 i think they're up to. get it here
http://java.sun.com/j2se/1.4/download.html
After you d/l it be sure to uninstall the 1.3 client and restart limewire ... it will say that it cant find its client ... direct it to the 1.4 client and you are set.
According to the microsoft knowledge base ... windows XP shipped with some serious Java problems ... one couldn't even install J++ from Microsoft's own visual studio without casuing the infamous blue screen of death ... however last month or so ... Sun released the XP compatable version Java ... follow the above directions and you'll be set.