The closed source drivers haven't supported the X1400 in a while. The old versions that do don't run on any recent distros because of kernel incompatibilities.

It's not a hardware problem. We have lots of T60s at work and they all the same problem in Ubuntu 10.04. The open source driver support for the 1400 is not good. I have to disable most of Compiz to avoid glitches. ATI's closed source driver worked a little better in some ways but they dropped support for those chipsets and the old drivers don't work on current kernels.