32 vs. 64 bit Windows

Recently, I've decided to conduct a few small experiments. I'm taking some older, slower computers and re-installing Windows 7. I'm configuring each system with 3 GB of RAM and 32-bit Windows 7. I'm comparing their performance to same systems configured with 4 GB of RAM and 64-bit Windows 7.

Will 1 GB of RAM make any difference in performance? Given that a 32-bit OS can only work with 3 GB of RAM, what happens if you take that same system and install a 64-bit OS and boost the RAM?

If these systems were faster, then the 64-bit OS with more RAM would easily outperform the 32-bit OS. However, my first test machine is a laptop that has an Intel Core 2 Duo CPU L9400 running @ 1.86 GHz. Let's see how it does, so stay tuned.