Hi, cannabiss6 welcome.
To run a 64-bit version of Windows, your computer must have a 64-bit-capable processor. If you are unsure whether your processor is 64-bit-capable, do the following:
1) Go to Start Menu and Type 'Windows Experience Index' and then Click on it.
2) If you not rated your system rate it. Otherwise if you already rated click on "View and print detailed performance and system information".
In the System section, you can see what type of operating system you're currently running under System type, and whether or not you can run a 64-bit version of Windows under 64-bit capable. (If your computer is already running a 64-bit version of Windows, you won't see the 64-bit capable listing.)
If you found that your processor is capable. Then you can install Win 7 x64 bit. Otherwise buy a processor which is 64 bit capable.