i dont know if this is right but i think those cards dont have support for vista. im pretty sure on the side of the retail box it doesn't say vista. you migth want to look on ati's website for drivers supporting vista. dont know if the helps.
I've 2 saffire boards X1300 with 512 MB each, crossfire eneabled. Vista says that I have 1279 mb graphic memory but only 767 mb of shared memory, and 512 mb of dedicated memory? Is it wrong?
using catalyst 7.2)
motherboard P5W DH Deluxe (asus)
Intel CPU 6400 @ 2.13GHz, 2128 Mhz,
RAM MEM: 2 GB (DDR2 - 533)