Is Windows 10 32 bit good for iMac 4,1 running Bootcamp? I have an iMac 4,1, 2Gb RAM and installed Bootcamp. 
Is Windows 10 Home Premium 32 bit good for that machine? Or is it too heavy, better install Windows 7 Home Basic 32 bit?
The latest supported Windows version for that machine is Windows 7, 32-bit.

There will be no drivers available for Windows 10.

Ref: Everymac