There are a couple of things you can do.
1) The time tracking program located here (
http://www.allnetic.com/?Tracker) is pretty good and easy to use -- not tied in to UR but still worth looking at.
2) Change your note template to include the attribute "Work Total" and manual adjust this field each time you change to another project. -- Rough but workable.
Item 1 above is far more accurate and provides for a history of dates and times you actually worked on a project, which I think could be exported out and then imported back into UR as a child note to your project notes.
Anyway, good luck in the hunt.
<Ralph>