i love this one it works really well and has some very good preset profiles that will increase your performance quite a bit.if you dont really know how to set up all those features in offered by radeon this is for you http://www.tweakfiles.com/video/raidontweaker.html this is the link to raid on tweaker 5.1 enjoy
I use powerstrip, but I think I'm gonna try the Raid on Tweaker that Harderclock mentioned. My advise would be to try them both and check out rage3d.com (or is it .net, I forget the addy, I'd look it up for you but I'm at work, maybe someone else here can tell you what it is for sure). See what other utilities they have and try them out as well. That way you can decide which works best for you/which you like the most. That is what I did, and I settled on powerstrip, but I hadn't heard of Raid on Tweaker so I'm gonna give that a try.
Good luck, and let us know what you find/ how you do overclockin'.