Because it is the 32-bit player packaged for the 64-bit version of XP. If you try to install the x86 version on XP x64, it won't work. You need the version packaged for XP x64. To differentiate this version of WMP 11 from one for 32-bit XP, they gave it the "64-bit" moniker. The only true 64-bit version of WMP is in Vista.