There are some minor differences between the 32-bit and 64-bit versions, but in case of a non-professional user it all goes down to the RAM. If you have 4 and more GB of RAM you should install a 64-bit version (because a 32-bit system won't recognize more than 3 GB of RAM). Remember that Microsoft complicated everything by calling the x32 version "x86", so don't make a mistake when choosing ;)