HP PhotoSmart 7760 and Airport Extreme Printing
The HP PhotoSmart 7760 is not supported for use with the Airport Express/Airport Extreme Base Station with HP's own printer driver.
It will sort of work with the CUPS+Gimp-Print DeskJet 990 driver.
The Photosmart 7760 will "sort of" work with the DeskJet 990 CUPS+Gimp-Print third party printer driver. In the Printer Setup Utility, Add a new printer selecting "IP Printing" and the socket/JetDirect printer type, to IP address 10.0.1.1 (the default IP address of the Airport Extreme). Then select the CUPS+Gimp-Print driver for the DeskJet 990C.
Note this HP Page if you have a HP PhotoSmart or All-in-One printer.