I want to share an HP 7760 on an XP with Win 7

To get ahead of myself and answer your question first, your Win 7 machine may automatically load a driver for your shared printer.

Please have a look at the procedure below: (these instructions assume that your XP machine is sharing the HP printer and that your Win 7 laptop can "see" your network and the shared printer connected to your XP desktop computer)

On the Win7 machine, follow these steps:

1) In "Control Panel" click "Add local printer"
2) Create New Port > Local port
3) Port Name is "\\xpcomputername\printername" - without the quotes

(insert the XP's real network name and your printer's real name in the above location)

4) Click <OK>

5) Windows 7 should automatically load a driver allowing you to print on the HP connected to the XP from the Win7 laptop.

I hope this helps!