I have noticed that people are searching for Karmic Koala and the video card ATI Radeon HD3650. As a user of both (the os and the card) I can say that they work great. The only problem with mine was that when I installed the driver The screen resolution was too big for my screen and in between flickers of my screen I set the resolution low enough for my monitor. In the end it works out though I couldn’t use Ubuntu 9.04 on the computer with the ATI Radeon HD3650 because it did not support it.
I find it is good to know since I use this computer a lot and is in need of being really fast. I find Ubuntu much faster then any other OS that I have tried except Xubuntu which is a lighter weight OS.