1. Click Start - Control Panel - System and Maintenance - Device Manager
2. When the DM opens, under display adapters, right-click the standard VGA and choose properties.
3. On the driver tab, click update driver
4. Click Browse my computer for driver software
5. Click let me pick from a list of device drivers on my computer
6. Untick 'Show compatible hardware', then scroll down to Intel Corporation and on the right side, click 'Intel® 82865G Graphics Controller (Microsoft Corporation -XDDM)', then next and OK the old style warnings about the driver not being compatible etc. etc. etc.
It won't do Aero but the display is definitely accelerated, Vista is stable and the performance index goes up a lot.