A:Answer I believe this drive can solve your issues. This drive is powered and runs with just a 3.0 USB cable. Don't worry if you don't have a 3.0 USB port on your OptiPlex because it is downward compatible to 2.0 without any intervention from your part. When plugged in, your system will find this drive and assign a drive letter to it. From there, as an external drive you can independently put files on it which can be accessed just like your internal drive, or transfer all of your files from your now filled up HD to the My Passport drive and open your internal drive up for more current work, do a backup of your user files (WD provides this software included with the drive) or with of the use cloning software (not provided by WD; I would recommend cloning your internal hard drive of your PC in case your internal drive fails, by cloning you can recover your O/S, Programs and Data files without losing a thing. Easiest and most reliable program I found to do this is with a product called Acronis True Image 2016.) Cloned drive information can be retrieved but don't think they are directly accessible as working documents/files.
I love this drive because of it's reliability, compactness and ease of use. If your seeking however speed from a hard drive I would recommending purchasing an SSD (solid state drive) drive which is quite expensive these days (has no moving parts) and is extremely light weight. Or another choice is to purchase an internal drive that runs at 7600 rpm vs 5400 rpm but are physical hard drives. For more detailed information on this see:
http://www.buildcomputers.net/ssd-vs-hdd.html
Good luck!