Is your LW connected properly (all green/blue connection bars)???

Make sure that Vista's firewall is configured to allow LW.
In LW go tools > options > advanced > firewall. Change LW's listening port to 65000 > Apply > ok.

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 See whether that helps your speeds.
TalkTalk UK ISP blocking p2p


You could also try port forwarding for your router. The instructions are here.
Port Forwarding for the Huawei EchoLife-HG520s

Make sure that you've set up a static IP address first (those instructions have a link to static IP setup). LW's listening port, port in the 'manual port forward' box & port forwarded within the router should all be the same number.