3.31 is intended to deal with issues that arose as between 10.3.3 and 10.3.9
it doesnt have any new features.
what happened is that major changes in graphics were made silently by apple without any forewarning or api changes.
i have no clue what they changed. but it broke some things.

3.31 also works on tiger. necessitated by apple depreciating some functionality on tiger - which requires support for ati and nvidia.

what makes it a beta is that apple continuously has made dozens of changes to hardware and software all last year - including major architecture changes in both hardware and software.
and all these changes cannot possibly be tested for.

tiger jun05 broke low level support in the os for scsi and video input - in the os - which wasnt fixed until 10.4.3

the change to pci-express in oct05 again throws another spanner in here -as all pci cards have to be changed- and all drivers have to be changed and retested.
both atto and decklink have not had hardware available or drivers ready.
apple moved over to nvidia on the pci-express machines - but the nvidia drivers - didnt really work properly.
10.4.4 only just makes the nvidia cards work properly.

as far as ati drivers?
quite honestly - its not been possible to give any advice - as they changed so rapidly - its just not been possible to make any kindof sense of how these things interact with any control panels.
then in oct05 the change to pci express - and no ati boards -

just too many changes. constantly.
and apple gives developers no access to hardware in advance of release to the public.
---

pci-express cards.

the 6600 is a bit of a downgrade in performance from the 9800/x800
the 7800 only became available just before christmas
the 4500 is a 2 pci-slot monster - that caused kernel panics on my machine.....