Kernel driver in use: i915 Kernel modules: i915
The i915 driver is fairly rock solid - virtually all desktop machines these days have on-board Intel video, it's the lowest common denominator. And your chipset is not exactly cutting edge stuff.
Are there any errors in the logs - either kernel logs or X logs?
For some reason you say you disliked Gnome - but does Gnome show issues (they use the same video driver)?
A long shot is the theme. Are you using some non-standard theme on your desktop?
Finally, do you have a spare graphics card you could try in the machine? (This is just to make sure there's no hardware problem.)
P.