I'm using a Dell Latitude D400 - Pentium M 1.4GHz, 1GB RAM and integrated Intel graphics with the 830 adaptor.
There seem to be several people with working methods here but I've not seen this one so here it is...
I downloaded the RAR of the Vista
driver from this site.
Installed it manually through Device manager and was left with two adaptors - the Intel one and the standard VGA. I only had basic VGA resolution.
After a reboot I went to the standard VGA device and updated the
driver choosing from a list. I chose the same
driver so that I had two instances of Intel (R) 8252/8255 GM/GME Graphics Controller (MS Corp - XDDM).
Another reboot later and I have full native resolution. No Aero obviously but it beats VGA mode.
Plus it seems stable so far at 15 minutes in. After a reboot it's also holding the driver.