Your problem is your ISP which is apparently blocking the popular gnutella servers. Either you try connecting to another address you know (maybe the one of a friend) or you trym getting a gnutella.net file here:
ftp://whitedragon.dyndns.org/gnutella.net
(online 16 hours a day)
You will have to copy the file into your LimeWire directory and restart LimeWire (it will only work with LimeWire 2.5 or later). Hopefully you will get connected. Though you won't have much of a chance if your ISP did a good job at blocking gnutella access for its users.