Made a new PC and now I am using the same HD I did as my other PC. Do I need to wipe the memory prior to boot up on my new PC or can I just install the OS again w/o uninstalling anything that was stored on my old PC?
usually you can just install over it.. unless you had vista and are now installing xp or something like that. so you cant downgrade without reformatting first.
in your case you will be installing the same OS. so yes it will be fine.
How do you know the USB ports are not working if theres no OS installed? If your talking about a USB keyboard you need to go into the Bios and enable USB keyboard support.