I've been using Time Stamps from the following website:
http://www.syntap.com
It allows me to get the "granularity" that I need to time individual tasks for one of my clients that has a need for very detailed information. Other timers that I used were just too clunky for me to use. I hit the button to start, I hit the button to stop. I have the ability to make notes as needed and can export the information as a deliminated text file or .XML file as needed or print to PDF as well.
One thing that I really appreciate is not having to be tied up to the internet while working. I find that sometimes Outlook "hangs" the system a bit along with continuous virus scan updates etc. We have to have the utilities, but we do not have to be "slave" to them.
I am using the 3.22.2007-1206 beta version on Windows XP Pro with no problems.
BTW, the price is right: FREE
Good luck with your search.
tctsco