CopyPasta from geekdrop:
http://geekdrop.com/content/how-to-brid ... -windows-7
Watch that last step though, its a little tricky to get both connections highlighted together. You may have to play around with the window's settings to get them side by side. Note also that if you're trying this with BerryBoot it may not work (I tried it yesterday). But for anything else, it works very well in my experience.
Here's how to bridge network connections in Windows 7
Plug-in your game console (XBOXXBOX, WII, PS3PS3, etc.) or anything else you're wanting to bridge, and allow it to acquire an IP address.
Click on the Windows button and type "Network and sharing center", then hit the enter key.
Then on the left, under "manage wireless networks", should see "change adapter settings". Click on that.
Right-click "Local area connection", disable it.
Right-click "Local area connection" again, click "properties".
There should be a tab that says "Sharing", Click that tab.
There should be a box that says "Allow other network users to connect through this computers internet connection". uncheck that (if it's checked).
Click "ok", and then right-click "local area connection", enable it.
Select both your wireless network connection and the local area connection, right-click, it should have an option to bridge connections. Click that and you should be all set!
What is a Network Bridge?
It is a way of just letting one device pass through another's network connection. No routing or NAT is needed.