I ran into this same problem some time back. Frustrating!!!
BUT one of the OTHER links in the knowledge base let me get to the order page. The disk will cost you ~ $10. I had gotten software previously from a free site (driverguide.com, I think) but I was having problems with it crashing the entire system sometimes when I tried to scan something. Reinstalling from the HP disk made that a little less frequent, but it still happens. Sigh.
ALSO there's other bad news: these things won't run under Windows 7 (don't know about Vista) because the drivers aren't compatible and they aren't being updated.
Also FYI, I was able to get cartridges pretty inexpensively on Ebay, along with a roller kit. Instructions for the latter are online.
Hope this all helps you!