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

Do you see the firewall icon (brick wall in front of the blue globe)?
Who is your ISP?

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