Conman,
To work, Hardware Acceleration depends on several factors. One of them is
that the motherboard chipset drivers must be compatible with Vista. Vista
may include chipset drivers for some chipsets, but not all. Chipset drivers
can be downloaded from the motherboard manufacturer's website. Each
motherboard has its own unique drivers. If you have a VIA based motherboard,
those drivers would be the 4-in-one drivers. Be sure to use the correct
chipset drivers for your motherboard. It does no harm to reinstall those
drivers, even if you already have the correct ones. I think Vista installs
Direct X 10, which is backwards compatible with prior versions of DX video
cards, so you should be OK there.
Let us know what happens,