The driver is already available in Windows Vista, the above link provides
instructions.
HP certainly says that but they go on to say:
<< Using the advanced printer functions
You might find that some of the advanced features are no longer available
when using this basic driver. You can upgrade to an HP product that is fully
compatible with Windows Vista if the advanced features are necessary. >>
Instead of saying "the driver" they really ought to say "a driver" or even
"a limited driver" ......
It's a pity since HP do a pretty good job of looking after customers' well-
being.