if you have a Intel® CoreTM 2 Duo Processor it's 64 bit compatible.

Thanks for the info. I've got the Home Premium disk (Academic) and it did not ask whether I wanted to install 64-bit. So I installed 32-bit. Then I ordered and received the 64-bit upgrade disk from Microsoft. When I run setup it gives an error message. So, how do I install 64-bit?