Worflow Overdue report

We have a release strategy for PO with about 5 steps. I am trying to find/develop a report that shows the Workflow Items that have been in somebody's inbox for more than 7 days.....does anybody know of the tables, or report that provides this?

I see these tables...

SWWWIHEAD, SWWLOGHIST ....any others ??

Example:

PO Number | Stage | Name of Approver | Since

3456 2 johndoe 6/18/2007