Also there's some better security features in x64.
Address Space Layout Randomization
ASLR is a security feature that causes a program’s data locations to be randomly arranged in memory. Before ASLR, a program’s data locations in memory could be predictable, which made attacks on a program much easier. With ASLR, an attacker has to guess the correct location in memory when trying to exploit a vulnerability in a program. An incorrect guess may result in the program crashing, so the attacker won’t be able to try again.
This security feature is also used on 32-bit versions of Windows and other operating systems, but it’s much more powerful on 64-bit versions of Windows. A 64-bit system has a much larger address space than a 32-bit system, making ASLR that much more effective.