I have a laptop running Win 7 Home Premium SP1 64-bit. 4 GB Ram I had shrunk the 581.42 GB (C: ), and created a 284241 MB partition intended to install Win 8 into. I have a retail Win 8 Pro upgrade version which comes with a 32-bit and a 64-bit disc. Can I use anyone of the 2 or do I have to use 64-bit disc ? Thank you.