So I'm planning to Upgrade from my Windows 7 ( Enterprise 64-bit SP1) to Windows 10 64 pro. My C partition where windows 7 is installed on is practically empty. Only some programs are installed on it and are easily re downloadable like Chrome, Nvidia drivers etc. But these aren't the ones i'm worried about. The reason C is practically empty is because I install every program on my second hard drive. These include Visual Studio, VM, Video games etc. which are very important. I fear that some of these programs save their settings and registry info on C and if I format C they'll stop working and show things like "This program has stopped working" or " error 0xc0000..7" which I'm really not in the mood to fix. So is there a reason to worry? I'd appreciate every suggestion. Thanks.