I just upgraded from a Lenovo ThinkPad running Windows XP to a Dell Latitude laptop running Windows 7. Skype worked fine on old laptop.
I installed Skype. I can make a video call and see the other person, but there is no sound in either direction. I tried the Echo/Sound test routine on both. Does just what you'd expect on old laptop. No sound on new Dell. The sound bars do move, but there is no sound.
I tried the Firewall fix, but that did not solve the problem. Christmas is right around the corner, and I really need this to be working.
If you go to Tools -> Options -Audio settings, what settings do you see for Microphone and Speakers? Also, what do you have for the corresponding settings in Windows Sound Control panel?