You can set up a specific tab order with Acrobat. The exact procedure depends on which version of Acrobat you have. In 9/10/11, you have to go into form editing mode and drag the fields that appear in the list in the order you want.
Acrobat 11 allows you to select multiple fields at once when doing this. It also has a user preference that prevents the automatic reordering of the tab order as you create and edit the form, which is a good thing.