The 20D is the same as the 10D 1.6x and thus cannot be used successfully with Panoweaver. Unless someone can prove differently by posting some "real" sample pic's for us to stitch.
You can stitch the images BUT their are area's that need quite a lot of Photoshop work on the overlap (or lack there of!).
If people are interested I could post a sample showing the issues I have come across trying to stitch this type (10D + Sigma 8mm) 3 x Fisheye images.