i currently have windows 7 on a 1TB HDD, i'm thinking about adding another HDD or maybe even SSD to my pc, i'm going to be installing windows 7 on to this too, but when i set up my new HDD or SSD i will unplug my current one so it wont get in the way of installation files etc, but when i plug it back in will both drives collide as i imagine they will be both called C:?
If you want to make an exact backup of your C: drive, you can clone it. However use only one hard disk in the system and you may keep the clone as a spare. This has the drawback that Windows updates are installed every month, and the clone will be out of date.
However, doing so is not a substitute for regular and frequent backups.
When you partition and format the drive you will assign it a drive letter. After you connect the drive (assuming it is detected properly by your BIOS) you can go to Start, Right click Computer, Manage and find disk management on the left-hand side. Find your new volume, right click and format. Assign the drive letter and you should see the drive available.
You can always go into Disk Management and set this up. But there cannot and won't be two Drives with the (C: ) letter, it will change by exemple to (F: ) or (E: ) etc. I installed my SSD today and copied my old HDD to my new SSD, and it automatically changed it once i switched the boot drive on the BIOS, you should just make sure to look into that, though. Goodluck !
And unless you want to backup, i'd make sure to Format the old Boot Drive ... Just making sure to avoid Conflict, otherwise, i do not know, i am not a complete knowledged person for that. But that is what i know, since i had the chance to do it.