You need to remove old HDD and replace it by SSD. Then, you can install Win 8 (either from files already set in SSD, or from USB - I recommend the latter). DO NOT have both hard drivers in bays while installing Win 8 in SSD. You should only have ONE drive on the computer. After all is set, then you can add the second one and format it. Also, you might have to make BIOS changes letting it know that the HDD is the slave one. There is a couple threads on this forum that already discussed that.