Hi Grahame. Check out this link.
Lexmark 2500 drivers for Windows 7 RC Build 7100 - Vista Forums
I have an x1150 that wouldn't work with Windows 7, but with the Vista x64 driver it would (and I am running windows 7 x86)!
That was found after a google search, but unfortunately, is on a Vista forum instead of here where it is most needed.