Backup HDD

Should I have my backup HDD internally connected with SATA 300 or should I have it externally connected, when needed with USB 2.

 

Always connected makes it vulnerable to malicious stuff, also general wear.
Internal you can schedule jobs to run without having to remember to plug the drive in all the time.
External a bit safer, but I'd upgrade to USB 3 or use eSATA for better speed.

Backup - imaging or just files?

 

Disc image and files, both.

I have a USB 3 socket on the front of the desktop's case. How can I use that and what do I need to adapt my SATA HDD to the USB socket and an external MOLEX power plug?

 

Both and more. You should have layers of backups to ensure recovery.

I personally do not like USB connected external drives. USB is just not consistently reliable. Forums are swamped with users complaining they can no longer access their external USB drive. But still, they are convenient and are nice when they do work.

But internally connected drives are more reliable - or the connection is anyway. And generally much faster too.

My choice for external drives would be a NAS (network attached storage) device. These are external drives connected to your network, not your computer. And the are particularly nice because all computers on your network can access and backup to them too. These can be stand-alone NAS drive devices, or what I did was repurpose my old XP system as network storage located in my basement.

That said, you should also have an off-site backup plan. If a badguy breaks into your home and steals your computer and your attached USB drive, can you recover? What if fire, tornado or flood destroys your home? So if you value your data, you should keep a backup at a trusted friends or neighbors house, or better yet, in a safe deposit box at your bank.

 

You can get an external case or a dock that connects USB 3. They come with power supplies.
http://www.newegg.com/Product/Produ...TMATCH&Description=drive+dock&N=-1&isNodeId=1
Or you can use a removable drive bay
http://www.newegg.com/Product/Produ...escription=hot+swap+drive+bay&N=-1&isNodeId=1