Download a file from here & see what speeds you get
http://www.magnetmix.com/video.shtml

You said your firewall settings are fine but do you see the firewall icon (brick wall)?

You could try deleting LW's preferences folder when LW's closed. See points 2 & 3 here
Fixes for LimeWire
Doing this will kill your settings within Options, you'll have to go back through & reset things afterwards