Switching to 64-bit will mean:
--Your computer can handle more than 4GB of RAM
--Your computer is more secure (Microsoft have added a lot of technologies to 64-bit to increase the security and stability, such as Kernel Patch Protection)
--You may notice a speed boost, depending on what programs you use
Potential problems:
--You'll have to reformat
--Occasionally you may come across a 32-bit program that won't work, or you may not be able to find drivers
If you don't mind reformatting, I would recommend going 64-bit