Reported for bump.
Side note - Mont & Blade player since the glory days, purchaser during the independent distro days, and big fan.
Never used Steam.
Warband disc prompts Steam install.
Installed Steam.
Steam updated the video drivers.
Which of course made my already-working-on-the-old-drivers Warband have these issues.
Short story - as with everything, auto-distribution and auto-update may seem like a good idea, but there is no substitute for research, recheck, and manual update for things you really, really enjoy. I blame myself.