Only use 1 software firewall...so if you're using the Trend Micro firewall, make sure that Vista's firewall is off. You don't need to disable your firewall, just make sure that it's allowing LW.

There are fixes to try in the thread below. If nothing there helps, post back with your system details (the thread has info about the details that we need).
If LW Will Not Connect

TalkTalk have caused problems for a lot of LW users. Use the forum search to look for talktalk & you'll find more threads, too.
It's Official - TalkTalk stopping P2P

Try using LW at different times of day...check the thread below
TalkTalk UK ISP blocking p2p