I'm currently running 64-bit Ubuntu on a computer that came with windows XP 32-bit. Is it possible to dual boot windows 32-bit with Ubuntu 64-bit?
If your computer has a CPU with 64bit instructions it does not mater what systems you have on your computer, they will not affect each other.
If your CPU has 64bit instructions you can run any 32 or 64 bit systems.
They wont interfere with each other.
Even tough you can install Windows after having Ubuntu installed already its much easier to install Windows and then after install Ubuntu since Ubuntu will configure dual boot for you but Windows will instead mess up your booting.
Yes, should be no problem at all, the OS for the most part are independent of each other