Building a new rig this weekend. Installing 8.1 onto a new hard drive, but am also putting my old Windows 7 drive in the computer (mainly so I have an easy way to copy over old files). After I install 8.1 and connect my old drive is there anything special I would have to do in order to use it? I mean it was a Windows 7 OS drive so it is already formatted to NTFS and stuff like that. I just want to make sure I am hooking it up correctly so I don't accidentally delete everything off of it.
Nothing special. It'll just show up as the D: drive or whatever.
You should make sure to set the drive with W7 on it below the one with W8 in the boot order in the motherboard firmware.