One of our students, Gwen Fisher, sent me a link to a free Interval timer application that downloads to your PC.
Download the program here
It is setup for Tabata Intervals but can easily be changed by going to the Timer menu and Set Timer. It starts with a "Let's get ready to rumble" then a bell rings to start and five bell chimes to stop. At the end, it makes a funny puke noise.
Have fun and train hard!