The single biggest difference is the amount of RAM that can be addressed.
32-bit Win7 Pro is limited to 4GB, while 64-bit is 192GB.
Unless you have apps that will only run on a 32-bit OS, you should go for 64-bit.
Using Software4Students is fine, as long as you actually have a qualifying student that will use the PC - this can be you, if you are currently a student, irrespective of age!
SD