How can i know which windows 32 or 64 bit is recommended for i3 core

Most all modern day CPU's support both 32 bit and 64 bit OS's. If you will be using more than 4 gig of memory, you must use a 64 bit OS.

I recommend 64 bit anyhow unless you have older devices that don't have 64 bit drivers for them.

EDIT:

I just noticed you posted this in the XP section. I do not recommend XP x64 as it doesn't have good driver support. Vista and 7 have excellent 64 bit support.