I'm on a Mac Pro 1,1 with the 7300 GT. Ever since installing the 10.6.3 combo update (I went from 10.6.2 -> 10.6.3) I was noticing weird issues with the Dock and window server (https://forums.macrumors.com/threads/896327/).
I reinstalled 10.6.3 (the original combo update) with no changes.
I just installed 10.6.3 v1.1 combo update. I was NOT offered it via Software Update, so I'm guessing that it really won't make a difference.
My build did go from 10D573 to 10D578.
-Kevin
Ive had some issues with the Dock as well in 10.6.3 and a 09 Mac Pro. However a bigger problem is a flickering second screen which is completely unusable in 10.6.3. I have a 10.6.2 restore running on a secondary disk because the screen works fine in that. Graphics card is Nvidia GT 120. Im thinking Ill try this Combo even though its supposed to be redundant.