Hello techiephobie, welcome to TSF!
Unfortunately, it seems that it's currently only for Windows 7 machines.
BlueStacks Launches Android App Player for Windows 7
Currently the App Player only works on Windows 7 machines. An OS X version for Mac is reportedly coming soon, but so far there's no word if the developer plans to support Linux, Windows Vista and Windows XP.
It's currently in the alpha stage of development, so there's no telling which way they may go as far as OS compatibility. From the looks of it, they are going with creating a Mac OS version, but that's all that seems viable. Perhaps later on there will be versions for Linux, Windows Vista, Windows XP, etc.