bigmck said:
I would vote for "Can't tell any difference".
I have observed the difference many times. I currently have a Lenovo G555 that I was marveling at the speed of, then remembered that the refurber I bought it from had loaded W7 x32. This holds true for entry level cpus with 2-3gb ram. And I would shudder to think what many of the Vista machines I work on, such as the compaq F700, would do with a 64 bit OS.

The later cpus seem to have overcome the 64bit overhead, esp with the help of an SSD. The HP Stream 11 is one such unit, running 64 bit on only 2gb of ram on a Celeron dual core.