I also have iTunes structure my music but I'm on mac osx.

You need LW 4.18.8 or 5 & iTunes 7.11.1 or 8. Otherwise LW's Library on DAAP will not work with iTunes. (Apple seemed to change the way iTunes' DAAP worked in v.7)
You will also need to have iTunes set to look for shared libraries; Edit menu > Preferences > Sharing. And you could check both options.
And in LW's settings, you need to have Tools > Options > iTunes set to 'Share My Music'

Only other alternate would be to use iTunes 6. However going backward in iTunes versions has its own headaches with personal library settings.