The guy was either lying or responsible for their idiot-infestation. No store that I know of would carry 32-bit Vista and not 64-bit.

32-bit and 64-bit are two separate versions of Vista, and they are quite incompatible with each other. It boils down to how much RAM your OS knows how to recognise, but there are many complications when it comes to drivers at the moment. You cannot install regular 32-bit drivers on a 64-bit OS, and the same vice-versa. For now, 32-bit is mostly sufficient but in the (pretty close, I'm guessing) future we'll probably see the development of 32-bit applications and drivers slow to a halt and 64-bits will be the new standard. But on the surface of it, there is no ostensible difference between 64-bit and 32-bit. They sure aren't the same thing though.