Double check that the XP firewall's allowing LW.
User Cant Connect - LimeWire

Try updating your Java to this verison. Use the JRE offline installer & remove your current LW version(s) before intalling this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Also delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.

Your modem doesn't seem to have a firewall. Are you using a router as well?