Double check that LW's allowed thru the XP firewall. You might also have a TSTT firewall.
New DSL company.
Try disabling that firewall, if it's there, & see if things improve.

Were you using Java 1.6.0_01 when you had a dialup connection? Some people have had trouble with that Java version. Try this one instead. Use the JRE offline installer & remove any other Java versions before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

When you set up port forwarding, did you set up a static IP address first? You'll have to. Go back through these instructions & double check your settings.
Port Forwarding for the Paradyne 6211-I2
LW's listening port, port in the 'manual port forward' box & port forwarded within the router all have to be the same number

Another thing to do is 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.