Try downloading from HP Deskscan 2.9 and installing that.
No guranteee that it will work with your scanner but I'm using it with
my old HP SJ5P under VISTA and it's working fine, scanning from the HP
Scanning and Copying utilities. But you can't use the VISTA Scan and
FAX.
http://h10025.www1.hp.com/ewfrf/wc/softwareList?
os=228&lc=en&cc=us&dlc=en&product=58976&lang=en
If clicking on tht URL does not work for you, copy the two bits into
the address box of your browser so that they join up and use (GO) or if
all else fails go to the first HP Support Page and put Deskscan 2.9 in
the Search Box at the top.
Download the second item:
ScanJet Scanners DeskScan 2.9 and Copy Utility