what version of skype are you using? there is a beta release just come out again
Download the beta version of Skype for Windows
and they state this>
System requirements
PC running Windows XP, Vista or 7.
Internet connection (broadband is best, GPRS is not supported for voice calls, and results may vary on a satellite connection).
Speakers and microphone – built-in or separate.
For voice and video calls we recommend a computer with at least a 1GHz processor, 256 MB RAM and of course a webcam.
For High Definition (HD) video calls both you and the person you're talking to need Skype 4.2 for Windows or higher, plus HD webcams. You'll also need a high-speed broadband connection (we recommend sustained 1.2 Mbps symmetrical bandwidth or higher) and a PC with at least a 2.0 GHz Core2Duo or equivalent processor.
Technical details
Version 5.0.0.123 File size 20 MB. Beta release. Release date: September 2, 2010. File name: SkypeSetup-Beta.exe