Recently I had to replace my motherboard on my prebuilt HP computer. Since I need a new Windows 7, I ordered a copy of just the disc for Professional. I was wondering if it would be possible to somehow make my Professional into Home premium and then use the license key that came with my computer for Home Premium, without having to purchase a new license key, or returning Professional and just ordering Home premium instead. BTW, I haven't installed the new disc yet. I don't think it will work, but I guess I'm just hoping for the best.