First of all, Talk Talk are known to throttle p2p so that could explain your slow download speeds. Check out this thread & the links within it.
http://www.gnutellaforums.com/showth...light=talktalk

http://www.the-scream.co.uk/forums/t21901.html

Don't use 2 software firewalls together, they'll interfere with each other. Pick one, configure it to allow LW & turn the other one off.

Try updating your Java. Use the JRE offline installer & remove your old Java version before you install the new one.
http://java.sun.com/javase/downloads/index.jsp

Do you mean that the firewall icon appears for 10 secs & then disappears? If the interface disappeared I don't think you'd be able to use LW

If your firewall icon's disappearing, that's good. Just in case, what's the model of your Linksys? You could try changing LW's listening port (tools > options > advanced > firewall config) to 64049, or something in the range of 49152 - 65535. Any ports forwarded thru a router will have to change as well

In LW tools > options > bug reports > view example. Scroll down to 'recieved incoming this session'. If it's false, you can't recieve incoming connections from other computers & so people won't be able to download from you.

Do the other computers have the same slow download problem? If they do, I'd be thinking it's a Talk Talk issue. Have a look through those threads & see what you think.