Your first and biggest profit is in using 64Bit is could use more than 4GB Ram. I mean you can get a good performance on CPU and graphics card. We will share reasons of it.
Some weaker devices such like old Computers or netbooks dont support 64 Bit.Actually they dont need to 64Bit. Because 64Bit is not a magic, it just provides devices to use their exactly performance.
Today 64Bit software and hardware support become common and robust. In the comimng days 32 will be abandoned bit by bit. 64 Bit operating system is required to use full performance to devices.
If you buy your computer in last three years it is probably compatible and it has benefits to transition 64Bit Operating System.After now do not hesitate to use 64 Bit Operating System when you buy a new computer. New computer can work full performance with 64 Bit opearating System.