I then found something called "NXtest10.zip", homepage is here. <BR>Running the 32-bit executable from the archive yields a dialog stating I don't have DEP enabled.

I doubt many folks would see much of a performance difference between 32-bit and 64-bit Windows on the same hardware unless you are using software that can specifically use 64-bit dynamic range to ...

VirtualBox is flexible enough to handle many types of 32-bit and 64-bit configurations. If you need to run a 32-bit version of XP in a 64-bit host, you can do that without any problems.