When I load a XDCAM disk into vegas each clip is prefixed by the letter C when I load a second disk to the same project it is also using the letter C so I have two C1. C2 ect how do I change my prefix letters in vegas 8
Thomas

Vegas isn't naming the disc, your camera is. You can change the name of the disc, but realize you'll lose your proxy shifting ability when you do.
Change the reel/disc name in the XDCAM's menus if you don't want to see the disc name being similar.