Ther may only be certain bit version drivers
for that machine.
If so, he needs the correct bit version of 7 installed - probably he could still use Pro - if he has a prod key for it - just install the correct bit version this time.
I'm a bit clueless when it comes to this stuff.. But isn't 32-bit less performing than 64-bit?
I wouldn't describe it that way.
It depends what your needs are.
There are some things a geek would want 64 bit windows for.
99% of people don't do those things.
You might argue that for most people , 32 bit is more suitable. It is smaller, uses fewer resources and has better compatibility with apps.