You can have both of them installed at the same time. No harm done. Probably most people new to Tray Tools keep CCC for a while until they are familiar with Tray Tools. You do have to do some kind of hack to use it with Vista so you don't have to deal with UAC all the time. I was never all that impressed with it. It was useful for setting fan speeds on the 1900XTX but if you don't overclock there aren't that many things that it does that CCC doesn't. It is less taxing on your system than CCC but with a reasonably powerful system, so what. It does have more features than CCC but the only thing I thought would be useful was Triple Buffering and I could never get it to work on the 1900. I have found the latest versions of CCC to be way faster than they were in the past, loads instantly for me. Tray Tools was always buggy for me, always re-installing it because options quit working or were greyed out. YMMV