Here's a nice regular expression to use for capturing URLs:

  1. ((https?|ftp|gopher|telnet|file|notes|ms-help):((//)|(\\\\))+[\w\d:#@%/;$()~_?\+-=\\\.&])
  2. ((https?|ftp|gopher|telnet|file|notes|ms-help):((//)|(\\\\))+[\w\d:#@%/;$()~_?\+-=\\\.&]*\.full\.gif)  

The first captures regular URLs.
The second captures URLs that ends in .full.gif