I just wait till the rubber band snaps then put a new one on with a non-interference engine. On my ZX3 the timing cover's off so I'll probably notice when it's starting to go out (you usually get chewed up teeth and/or fraying between the plies of the belt right before it goes).
I'd just wait it out. Buy a new belt at 80 or 90k and keep it in a cool dark place so you can just tow it home and toss it on when it decides to go. Or if you're daring, keep it by your spare tire and keep tools in the car.
Do swap the timing belt, look at these instructions, but ignore the parts about removing the cam gears and valve cover. It covers removal and installation of the timing belt and adjustment of the tensioner:
http://www.focushacks.com/index.php?modid=17
I've had to post this enough times, I should probably omit the cam gear stuff and re-post it on my site as a timing belt howto.