You write "Win7 doesn't ask for the location of the driver". That's strange. If I go to Start>Devices and Printers>Add a printer, the Add Printer wizard after two dialog screens (local printer, lpt1) I get a screen with (bottom right) a 'Have disk' button to go the folder the driver is in (if it isn't in the list in the upper half). At 1:21 in http://www.youtube.com/watch?v=6kfK656hfJQ the mouse pointer is on exactly that button. Can't miss, unless your Windows 7 is corrupted.
But you would need a Windows 7 driver for this printer, while Bob says it doesn't exist.
You don't own Linux, and you don't own Virtual Box. That's true. The various Linux versions are owned by their makers, and Virtual Box is owned by Oracle, if I remember right. But since it both are free downloads, it's possible to use them without any costs involved.
And it's really possible to set up a 'classic' network with workgroups and enable file and printer sharing between Windows 7 and Windows XP, without ever using a homegroup. That's not really different from an XP to XP network. In fact, I've never even used a wizard to do it. You just enable the sharing on the target computer and connect from the other computer to file share or install a networked printer on the target computer from the same Add Printer wizard as I mentioned above.
So it's your choice to either dive in the virtual OS or printer sharing options, or buy a new printer.