@snerler -yes, I would say so. need both kexts loading for full gfx support.
@palmpje - there's nothing to upload, im just using the clean 10.6.4 + Graphics Update kexts, with a simple pci id tweak to match the card (in the two kexts mentioned above), and the EVOenabler kext from this thread with all instances of 'Alopias' replaced with 'Wormy'. Make sure your kext versions match the kernel, and you should be ok.
When getting the X1650 to work, I learned a couple of things:
1) The version of the kext must match the kernel - had some bad juju (corrupt screen etc) when they mismatched. Use the 10.6.4 kernel and the Snow Leo Gfx Update kexts.
2) Some ATI kexts dont have 64-bit code - 1800 seems to, 1600 does not, so that machine had to boot 32-bit kernel, whereas the machine with the 1800 can boot 64-bit clean.
3) Its best to use the latest kexts, clean and unmodified apart from any pci id changes you need.
The box with the X1650 is running with 10.6.4 kexts (including Snow Leopard Graphics Update) with only the couple id tweaks in plists and the EVOenabler from the first post in this thread with all instances of 'Alopias' replaced with 'Wormy'.