Changing 64 bits to 32 bits? Help please?

For reasons unbeknownst to me, I’m required to have one of the following for a job I’m trying to get:

* 32-bit Windows XP Home or Professional, Service Pack 3
* 32-bit Windows Vista Enterprise, Ultimate, Business, Home Premium with Service Pack 2
OR
* 32-bit Windows 7 Enterprise, Ultimate, Professional, and Home Premium

Okay, I’m running the Windows 7 Home Premium, but it’s 64 bits instead of 32. Is there anyway to revert back to 32-bits?

Thanks for any help you guys can offer.