32-bit programs run fine on a 64-bit Windows system using WOW64.
So you can run your 32bit program on Windows Vista 64bit.
More information about WOW64 : http://en.wikipedia.org/wiki/WOW64
EDIT: You do not have to worry about WOW64, its included on Vista 64bit. Just go ahead and run your 32bit app as you would normally.
Edited by Romeo29, 08 July 2009 - 04:50 PM.