Re: Vista! understanding..
Yeah... look here
"Windows Vista compatibility ensures optimal 3D graphical interface with upcoming Windows operating system."
Basically, Dx9 graphic cards should be able to take on Vista but just not as good as the Dx10 cards. I'm thinking Nvidia, and ATI will release driver updates to allow the graphic cards to be at least software compatible with Dx10, just like how the Ati 9250 can handle Dx9 games, while its only a Dx8 (hardware) graphics card.
Rig -- Emachines T5026, 3.06ghz P4, 300W Bestec PSU, 160 sata hd, 512mb dual channel 3200 ram @ 3-3-5-8, ATI Radeon 9250 pci, dual layer 16x dvd+/-rw.