Detect whether Office is 32bit or 64bit via the registry

Question

Now that Office also comes in a 64bit install, where in the registry do you find out if the version of Office installed is 32bit or 64bit?

Answer 1

I don't have a key called bitness in either of these folders. I do have a key called "default" in both of these folders and the value is "unset" My computer came with office 2010 starter (I assume 64 bit). I removed it and tried to do a full install of 32 bit office. I keep getting the following message. the file is incompatible, check to see whether you need x86 or x64 version of the program.

any advice for me?