| File sharing under Windows 7 Professional is a bit different than Windows XP. Here are a few pointers:
Go to Network and Sharing Center, on your computer you want to share stuff.
Make sure your network your connected to has been classified as a Home or work network NOT public (this will disable everything with file sharing).
If that is all good, go to "Change advanced sharing settings" on the left side of the screen. Expand Home or Work, make sure
Network discovery is ON
File and Printer sharing is ON
You might want to consider the pros and cons in turning Password Protected sharing off.