I don't have personal experience with the VC-200, but reports on another forum over the last year indicate that the C2100 + V-200 is not a good match. One poster had purchased the V-200 and was returning it immediately because test shots were poor, stating that "The CA is extensive and image quality falls off drastically toward the corners of the image." Another used the VC-200 on an E100RS (same 10x IS lens as the C2100) and found full tele shots to be "fuzzy," but that the VC-200 worked OK for close-ups; examples of those shots are shown here: http://homepage.mac.com/swegs/PhotoAlbum2.html
FYI, a list of potential teleconverters for the C2100 is here: http://members.cox.net/gandalfpublic/teleconverters.htm
That site also has links to tests using some of them, but the VC-200 isn't one of them. In addition, some of the information on the list is outdated. For example, it's nearly impossible to find two of the preferred TCs for the C2100, the A-200 and B-300. From personal experience, those two TCs work beautifully with the C2100 and E100.