If checkbox is checked then...

I'm doing data entry that involves checking a lot of check boxes in a web application. 

I'd like my script to tab through the checkboxes and, if a box is unchecked, check it by sending the spacebar.  The only problem is I don't know how to read if the box is already checked or not.

Any ideas?

EDIT:  I've looked at GUICtrlRead but I'm not sure how to make it work.