Q. Can I use a 32-bit device driver under 64-bit Windows 7?
A. No. A device driver is privileged code that runs in the same address space as the Windows kernel. As such, it needs to match the architecture of the kernel itself. Some manufacturers bundle both 32-bit and 64-bit drivers within a single installation package, leading casual observers to sometimes misreport that a 32-bit driver worked under 64-bit Windows. However, while 32-bit drivers are not directly supported in 64-bit Windows 7, 64-bit Windows 7 users can install 32-bit drivers in Windows XP Mode and use USB-based printers and other USB-based legacy devices with the Windows XP virtual machine.
Q. Can I use Windows XP Mode with 64-bit Windows 7?
A. Yes. Windows XP Mode is fully supported under 64-bit Windows 7. In fact, using a Virtual Machine Monitor (VMM), like the Windows Virtual PC 7 product that underlies Windows XP Mode, is one of the only ways to use a 32-bit device driver under 64-bit Windows. The lone caveat is that the device must use a USB interface; legacy hardware that uses a proprietary expansion card or dongle will likely not work with a VMM solution like Windows XP Mode.
Q. What exactly is Windows XP Mode, and how do I get it?
A. The simple answer is that Windows XP Mode is a virtual machine containing Windows XP SP3 that runs under Windows Virtual PC 7. It is available as a free download to users of Windows 7 Professional, Ultimate, and Enterprise editions.
The more precise answer is that Windows XP Mode is a native 64-bit application (actually, a series of 64-bit services and device drivers) that creates a separate, native 64-bit process emulating a 32-bit PC environment.