A:Answer On Hard Drives 1 TB (terabyte) = 1000 GBs (gigabytes). Please don't ask me why they lie and give you only 2.8 TBs on a "3 TB HD." I was told once, but don't remember. So if your kids are playing lots of games with High Definition 3D imagery then I would go to a 4 TB HD it will give them lots of room for saving games (being played), updating, and putting new games on. Hope that helps.