Thanks a lot so far, guys! That went really quick!
Since my onboard graphics card is all I have, I might well be stuck with the problem. Somewhere around the net, I've read about using S3D to edit texture properties, but I have never used S3D before and I don't know which values to edit. Since it's becoming less likely that there will be a quick and easy fix for my problem, I might look into that a little more.