For your firewalls, you'll need to configure them for LW to have access: http://www.limewire.com/english/content/firewalls.shtml

Your LW Preferences are found here: C:/Documents And Settings/your_username/.limewire & you'll need to delete the folder called .limewire. But make a note of all your LW settings 1st b/c you'll need to reset them. Also update to the most recent Jave: Java 1.5 (take the JRE)

For SP2 well ... it's given so many people headaches! See both Windows XP Service Pack 2 'Problems' - Some Info & also this SP2 & Limewire: relax, it works

Update your Java & delete your prefs & configure your firewalls & see how you go. If still no go, you may need to use the SP2 fixes.