32 bits or 64 bits IIS for Win 7

I enabled IIS on my Win 64 bits machine.

How do I know my IIS is 64 bits or 32 bits?

Are there any difference to load dll file for 32 bits or 64 bits machine?

Should I register .Net Frame according to 32 bits or 64 bits machine?

Your information and help is great appreciated,

Regards,

inungh,