Well, it's fairly comical that I stop by here and see another thread for a DIY motorized slider But I have been toying around with this project in my head for several months now and I finally got some time to do it. It's going to be in two parts - the first part is building essentially a standard "manual" non-motorized slider, and the second part is motorizing it. I've finished filming the second part, and hope to have the video live sometime next week. I'm very happy with the motor setup - it can pull 5lbs vertically with no problems.
Part I: https://www.youtube.com/watch?v=6xm3VVYVnEo