Originally posted by syringe
...Was the Best Buy guy selling snake oil or liquid gold?
You're diving into a very large issue here, that will require some knowledge on your part.
The world is slowly (but undeniably) heading towards the 64bit realm. Today, it is mostly surperfluous, and most applications (nearly all for the average home user) are only 32bit.
I would recommend you do some research to familiarize yourself with the 32bit and 64bit "realms," as it is going to be an increasingly relavent issue. The BestBuy guy was about 50/50, in that he was likely trying to make commission off of the higher-priced processor, but at the same time he is right in that it is going to be more common in days to come.