Got it fixed.
Dropped Mike's XF86Config file in my directory, changed the graphics driver to vesa, and it works beautifully.
The problem wasn't me accidentally bumping around the touchpad - the problem was that it kept resetting to the lower left-hand corner.
"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." -- Kristian Wilson, Nintendo, Inc, 1989