Task and Time management (tracking) software for Windows

Also a big fan of ManicTime, although the lack of task hierarchy did bug me too at first. I don't know if it would be good enough for what you need, but ManicTime does have an export feature -- you could always do an end of day "wrap-up" instead of interrupting your workflow when you change contexts.

I've found the best combination is to lay out tasks on paper at the beginning of the day, log time invisibly with ManicTime, and mark off tasks as I go. Low overhead and low stress.

[Edit] Actually, I use a variation of the Pomodoro Technique, which is worth looking into if you need a way to track time and stay on task. The PDF book on their site makes some good points about task tracking and overhead... basically, the returns for minute-by-minute task tracking aren't worth the extra effort. As long as you can approximate that level of record-keeping, it tends to be "good enough" for most people. Unless you bill by the minute of course. :)

The best time tracking application, as votes by the readers of Lifehacker, was Klok. You can read more about it here.

Try using ToDoList it has a bunch of features, like assigning task to users, splitting tasks into subtasks etc., in addition to the features you have mentioned. Most of all it's a freeware