I have a dual head geforce 6600 and the nvidia beta driver worked fine.
Then I added a 5200 as that was on the supported list. I got all three
monitors but when I checked, it had reverted to using the MS WDDM driver.
Recall that this nvidia on is supposed be a LDDM.
Updating to the LDDM driver broke the 5200. I reverted to the MS one and all
is fine. I orinally read that Vista only supported multiple adapters if they
all used the LDDM drivers but apparantly that is not the case.
Anyway, I have three monitors and they seem to work fine. Doesn't Vista try
to use the MS driver? Are you committed to the NVidia one? Not sure if you
lose anything.
-ck