How to get 64 bit on Windows 7 ?

I got a compaq laptop I'm trying to get iTunes on it but it says I have to download 64 bit. My other one is a compaq we didn't have to download anything to get iTunes on it. But the other one is having problems with the fan it's making loud whistling noise which scares me a little. It's a lot older than this one. How can I get 64 bit on the Windows 7 compaq laptop?

1. Buy Win 64
2. Install Win 64
DONE!

That means you're downloading the wrong version of iTunes. You already have 64 bit Win 7. You need to download the 64 bit version of iTunes, not the 32 bit version.

Whether your computer is 32 bit or 64 bit is determined by the process in it. Older processors are only able to understand commands up to 32 bits in length. Newer processors about to understand commands up to 64 bits in length. Windows comes in both a 32 bit and 64 bit version. A 32 bit version will run on a 64 bit computer, but a 64 bit version will not run on a 32 bit computer.

If you go into Windows Explorer (also called File Manager), right click on "(My) Computer", and go to "Properties" it will tell you whether you are running a 32 bit or a 64 bit OS. You will then need to download the version of iTune that matches your OS (32 bit or 64 bit.) Note: You can run the 32 bit version of a 64 bit computer.

If you go to the iTune download there will be an option for downloading either the 32 bit or 64 bit version of the program.

Yes you have to download the 64 bit version of itunes because your pc is 64 bit