Also- you have 12 GB RAM. with 32bit you'll only be able to use a little under 3 GB of that, wasting the other 9GB+. 64 is the only way to go with that system.
What you're really asking here is if you should waste 3/4 of your RAM by going with a 32-bit OS.
It would be absolute insanity to use a 32-bit OS on a system with 12GB of RAM.