CuPhone has announced an Echo-free USB to phone adapter for Skype, that seems simple to use: plug it into your computer, plug in your phone line, and plug in your phone.
Once that is done you can use your phone to make or receive both skype call and regular landline calls, plus the call quality will be improved because th adapter has built-in echo cancellation technology.
This is a product I would buy and use: my wife travels a lot on business and when she is in Asia or Europe we rely on skype computer to computer calls to save money, but that means we have to arrange calls times in advance so I can be at the computer with a headset on ready for the call. With this product I could just pick up my regular phone and talk.
The CuPhone Echo-free USB to phone adapter for Skype is available now for $34.