The guys at Labrats have a video up on how to increase the quality of your Skype calls. For both the video-phobic and the work-bound, here's a summary of what they talk about:
1. Set your router to give your Skype PC a static IP address.
2. Open a Skypish port to that static IP.
3. Give this port number to skype.
4. Set priority to that port over other ports/PCs. Only applicable if you have a router that supports this.
All straightforward stuff that may help you if you're having some quality problems with your Skype calls.