Which model printer?
Presume that you have downloaded the XP drivers and software. I have a different HP photosmart printer/scanner(not wireless) but hard networked and installs okay on Vista and XP with the right drivers/software.
HP software seems to me to be unnecessarily large and cumbersome to install. The Vista and Windows 7 versions have HP Solution Centre as the main control but XP still has HP Director. (Even the latest (September 09) version I downloaded last weekend)