Just installed my ThinkPad T400 using discrete graphics card with Ubuntu 9.04-beta. So far soo good! It just works, fabolous!
I was thinking of returning it for some personal reasons compared to my T43P, but I just might keep it!
Frame Rate w/ Discrete Graphics:
5458 frames in 5.0 seconds = 1090.804 FPS
5841 frames in 5.0 seconds = 1168.091 FPS
5834 frames in 5.0 seconds = 1166.787 FPS
5667 frames in 5.0 seconds = 1133.265 FPS
I am installing WindowsXP to be use side by side. I considerd dual boot but with 4GB of RAM, might as well just keep time side by side and add another 4GB when needed.
So far I am in love with it.