No, not Tray Tools. You need to download ATI Tool. Once you have downloaded this, make sure your default speeds are saved under DEFAULT profile. This should be 450/450. Now you can start increasing your core and memory speeds. As a reference, most guys are only going up to around 510/510. You can save your overclocking speeds in their own profile for when you're gaming.
NOTE:Any time you increase or decrease the speeds, you need to close the 3D window("Show 3D View") that shows that fuzzball thing. If you have that window open, and you click on SET CLOCK, your system will probably crash. Once you have clicked on SET CLOCK, then click on Scan for Artifacts, and then Show 3D View. Let it run and watch it for about 1-2 minutes. If you start to see some yellow pixels inside the little window, you are starting to get artifacts. Lower your speeds a little and try again.
DO NOT CLICK ON FIND MAX CORE AND MEM. These will raise your speeds to unstable levels.
Run 3dmark05 and 06 to test out your new OC'ed profile for stability and compare your scores between your default settings and your OC'ed. I think you will be very happy with the results. GOOD LUCK!