Can't run the WotLK version because it's 32bit, anything I can do?

I downloaded the WotLK content but upon clicking wow.exe, it gives me the "This version of this file is not compatible with the version of Windows you're running. Check your computer's system information to see whether you need an x86 (32-bit) or x64 (64-bit) verion of the program." error. I tried all the options for compatibility mode and none of them seemed to get it working. I am on 64bit Windows 7. Is there anything else I could try to make it work?