Installed the Skype 4 Beta to see if this works on Windows 7 I noticed the microphone volume was very low. I’d had a similar problem a while back, with Vista 64bit. Luckily the solution in my post Low mic volume in Vista 64bit solved the problem for Windows 7 as well.
Also not had any problems yet with the Skype Beta which you can get here. I’m not sure what to make of the new Skype UI, time will tell.