well, what are you getting? error messages, timeouts, what?
there's always the mighty command 'ping'. Go to Dos, then type
ping \\www.wrongplanet.net, and see if it gives you a response. Since Ubuntu works, we know that it's not the hardware, or the connection, so obviously it must be the drivers.
Then, there's always Googling the error code. Cut and paste the error message to a file, then boot up in Linux and log onto the web there. Paste it into the search box, and watch the results pour in. Surprisingly, you can come up with a lot of the stuff you're looking for, on the various forums out there. Getting the answer for free...well, that's a little harder.
It's a start.