I'll go out on a limb here if it works in vista 32 its gonna work in vista 64. Vista 64 emulates for 32 bit programs since just about all program yeh buy are still 32bit.

That being said there's a variaty of ways yeh can "dual boot" easist I would say is if yeh have 2 drives pull one install vista64 to the other add the other drive and then go into bios and switch the boot from option.