I have a HP Photosmart 7550 attached to a WinXP 32-bit machine acting as a print server on my home network. I did the following to install the HP Photosmart 7550 printer on my Win 7 64 bit Professional:
Devices and Printers
Add a printer
ADD A LOCAL PRINTER (My Win 7 machine is on the network away from the print server. The printer is not physically attached to the Win 7 machine.)
Create a new port. Type: Local port.
For Enter a port name: \\PrintServerComputerName\Photosmart7550ShareName
(If you get an error message here saying it can't connect, then you have issues seeing the shares over your network. Resolve this first before installing the printer. Make sure your security settings on the share is not restrictive, check your firewall settings, disable browser service if necessary, also check your network settings on the Windows 7 machine. Are you using password protect? Are you using homegroup? I got rid of them all.)
Once you get through you will be asked to assign a print driver. Before doing this, click on Windows Update button. Once the driver has been updated, find the driver HP Photosmart 7400 series. I did not use the Deskjet 5550 series that some other solutions claim to use. I just stuck with the Photosmart series.
Finish installing and print a test page.