Unplug the printer and plug into the Windows 7 machine and install the drivers
from windows update - put it back on the xp machine if thats the the arrangement or leave it on Windows 7. You should be ok either way if you know how to setup the rest - post back if you cant configure it to work.
If you do this it will install it automatically -
On the taskbar, click start
In the Search Programs and Files box , type change device installation .
Click Change device installation settings . The Device Installation Settings window opens.
If it is not already selected, select Yes, do this automatically (recommended) , and then click Save Changes