Dimmer switch and wiring it up?

[severe_bomber]

Like Jason said, get a lamp dimmer. They cost $10 and you don't have to rewire anything, you just plug the heat mat into the dimmer.

Thanks people. However, having hooked up the heatmat to the t-stat instead, it doesn't appear to be working! The mat isn't coming on at all. I've reverted back to running the bulb through the t-stat and will try a mat-stat. Will have to go and get one tomorrow. Yet another thing I hadn't bargained for! New owners - BEWARE!