Thank you for finding the discussion and the link - very helpful.
I've been putting this off for months, and just got it set up using Carl's excellent instructions on manage-this. It's a bit different for Vista (I pasted my comments to that discussion if you are using Vista) but still not hard to figure out. Now I wonder why it took me so long!
I decided to have it run every hour from 6 am to 11 pm, and delay until my computer had been idle for 10 minutes, so it doesn't go in the middle of my work; I tend to hit "F9" at the end of major changes anyway.
Lisa