Omnioutliner replacement for time estimation in windows

Question

I used to use OmniOutliner to do quick time estimates but as it is mac only I need a windows replacement for work.

Here's my use case: I want to be able to break down my projects into sub-tasks with work hour estimates that can be rolled up to each parent in the hierarchy. (the bold italic font indicates a calculated field).

• total              42h

• task 1             23h

  • subtask 1.1     3h

  • subtask 1.2    20h

• task 2             19h

  • subtask 2.1    16h

  • subtask 2.2     3h

  • subtask 2.2.1   3h

Any suggestions?