Not a stupid question.
If I am following your question correctly.
install a Windows 32 bit version on a 64 bit supported system, but you can not
install a 64 bit version on a 32 bit only supported system.
The processor has to support the 64 Bit OS, a 64 Bit processor can support a 32 bit, but a 32 bit processor can not support 64 bit.
Most would ask you why you would want to install the 32 bit on a 64 bit system, if you also have the 64 bit version, because 64 bit versions of OSes do not have as many vulnerabilities as the less secure 32 bit version.
Windows 7 retail packaged DVDs come with both a 32 bit and a separate 64 bit dvdrom disk. IMO
Edited by MrBruce1959, 17 May 2010 - 08:04 AM.