I'm a little old fashioned when it comes to tracking my time. I simply use a day planner and make note of the client, task and any notes and then the hours worked for that task. Most of my clients are billed monthly or bi-weekly and when I bill them for hours I highlight the time so I know it has been billed.

I also have Outlook 2007 with Business Contact Manager that allows for time and project management but so far this has been too time consuming and more work than necessary.