Hmnmm, I have a 7800GT and it's HUGE. That thing blocked off my Northbridge fan (good thing it was a skinny PCB board) and extend to my hard drive. Is that a microATX motheboard too?
A 7600GT should fit just fine. I have one on sitting my desk. The back edge of the card will probably extend to just where the end of the left most RAM slot is in your pic.