Has anything changed (software, hardware, ISP etc) since LW was working?

Don't forget that XP has it's own firewall. Configure it to allow LW
Firewall setup

Your Java's really old, try updating it. Use the JRE offline installer & remove your old Java version before you install the new one.
http://java.sun.com/javase/downloads/index.jsp

Have you always seen the firewall icon? How do you have the router set up (UPnP enabled, port forwarded or neither)?
Enable UPnP within the router. Then choose the UPnP option within LW's tools > options > advanced > firewall config.
If that doesn't help, try port forwarding. The instructions for your router are here
http://www.portforward.com/english/r...6/Limewire.htm

Don't forget to set up a static IP address first. Port forwarded within the router, LW's listening port, & port in the 'manual port forward' box have to all be the same number.

which Java one do i download because it's a kind of confusing page haha

JRE (Java Runtime Environment), it's the 4th download down the page. Make sure to use the offline installer.