I have an old white 13" MacBook (A1181) with the 32bit Intel Core Duo 2GHz processor. I believe this is the last 32bit processor Mac used. Anyway, I just install Windows 7 Enterprise natively and everything works fine except the sound card.
WARNING: Again, mine was a native install, not Bootcamp! So I moved everything I wanted off the MacBook before I installed Windows since the native install will require deleting the existing partitions, thus destroying any data within them.
When the installer runs just delete the existing partitions. The UI of the partitioning utility is not the greatest but I managed to figure out how to remove the existing partitions. Once the existing partitions have been deleted just click the "Next" button and the installer will use a default scheme to partition the disk.
It's that easy. Windows 7 runs great on the 7 year old MacBook with only 2GB of RAM.
Many folks recommend using the drivers exported from Bootcamp but they don't work in my case since they're all 64bit and I'm stuck with a 32bit processor. Still, the Windows installer found drivers for almost everything and the old MacBook does just fine without sound.