Did you have any trouble with any of the fixes in the help thread? Especially with deleting the gnutella.net file & deleting preferences folder?? Were you able to find the file & folder ok? And after deleting the prefs folder, did you go through LW's setup wizard all over again when you started LW?
Just in case you did have trouble, here's a link to a post with info about how another Vista user found & deleted their gnutella.net file...maybe it'll be easier to do it that way: LimeWire Forums - View Single Post - internet connection missing?

This worked (I have turbo charge connection), but I can't download anything.