I'm sure there's a way to do it in code by determining the report's size relative to that of the Access window, then using the MoveSize method to position the report in the center. My brain is too fuzzy to try to figure it out this late at night, tho.
A quick and dirty work-around would be to open the report in design view, then drag it to the center of the window (or as close as you can eyeball it), then save the report, then close it. The last position of the report is saved with it, so it will open in the same spot next time.
Ken S.