Dinosaur, I agree with the advice you got from Kurt. Getting a larger drive will not only help this issue but will almost certainly improve the function of your main computer- perhaps dramatically.
In the interim, I would download Cyber-D's auto-delete. This free little program is easy to set up and will automatically delete the back-ups created on your drive. Even after you get a larger drive, by using this program, you never have to remember to delete old back-ups; it will do it for you.
