Not with 4 Gb of RAM. you would need more than that to take advantage of the 64-bit processing. I would just stay with 32.
Hmmm, you'd need more RAM to take advantage of more RAM. 64bit processing works with any amount of RAM.
I would say, why not use the 64bit version? If you have plugins that don't come in 64bit yet then that would be a reason to stay with 32bit, but otherwise why not use 64bit?