Any suggestions for time planning (activity tracking) app?

As a business owner I find myself dealing with tons of different tasks that could be generally categorized into a few predefined categories. In order to keep my sanity and avoid stress I would like to limit how much time I spend on each category daily. Hence, I need a time planning and activity tracking app (ideally for Windows).
What I want this app to do is to store my list of categories and the maximum time per day pre-allocated for each category. Basically, when I start working on a task for a particular category (e.g. "web site updates"), I'll hit start button for this category and hit the end button when I'm finished. If I am still working on a task and nearing a time limit for this category I want a reminder e.g. "Nearing the daily limit for web site updates tasks: 5 min left". Finally, I want to be able to produce daily, weekly, or monthly reports on actual times spent on different categories.

Can anybody recommend the app matching this description?

 

Have you already checked this one out? Kind of what you're looking for:

http://apps.microsoft.com/windows/e..._12-apps-behind-the-strings_image_To-do-Prime

 

Not really. It requires me to schedule things in specific timeslots and I want flexibility. Otherwise I'd just use Outlook.

I am now playing with Toggl, it's an activity tracker that allows to have predefined categories and has start/stop watch but it doesn't have time pre-allocation and alerts (about to exceed allocated time). Otherwise, it's not bad.

 

My favorite tools to keep track of my time are, honestly, pen and paper. Here is some:
* Toggl
With this app, you say what you’re doing, start the timer, and stop it when you’re done
* TIME Planner
This free app combines scheduling and time tracking features for both work and personal activities
* Rescue Time
Running in the background on your computer or mobile device, the free version of RescueTime tracks minutes spent on various sites or applications.