Hi
I strongly advise you not to replace Win 8 with XP and even more strongly not XP 64 bit (which is based on Windows 2003 server)
XP is being made obsolete in April this year (32 bit & 64 bit + Win 2003)
BUY a copy of Windows 7 SP1, it can be downloaded from Microsoft BUT you still need to buy a licence & key
(Windows 7 has many versions:-
OEM system builder, OEM from PC Manufacturer,
retail, retail upgrade
then Home, Pro & Ultimate 32bit 64 bit etc (retail sets come with 32 & 64 bit DVD's)
Have you changed PC from one with Win 7 to a new one with Win 8 pre installed or upgraded from 7 to 8 but do not have the Win 7 disk to go back ?
The Windows software compatibility tester for Win 8 64 bit if run on Win 7 PC should say if this printer has the correct driver available
HP site says
Minimum system requirements
Windows 8, Windows 7 (32-bit/64-bit): 1 GB RAM; Windows Vista (32-bit/64-bit), Windows XP, Windows Server 2008 (32-bit/64-bit), Windows Server 2003: 512 MB RAM; all systems: 350 MB free hard disk space, CD-ROM drive, USB port;
Mac OS X v10.5, v10.6, v10.7; 256 MB RAM; 150 MB available hard disk space; CD-ROM drive; USB port
regards
Mike Barnes