There's a couple of things here. First, try the Print and scan doctor available here:
Print and Scan Doctor download
Assuming you haven't been able to install the software, the print and scan doctor should take you to the latest software on the web. You can also download and install the latest software here:
http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?softwareitem=mp-47754-2&cc=us&dlc=en&lc=en&...
also, you might want to consider upgrading to Windows 7. Vista is one of the most problematic OS's out there.
Let me know how the above goes.
Mike
Say "Thanks" by clicking the Kudos Star in the post that helped you.
I am an HP employee.