This unit is similar to what Apple incorporates into MacBook PRO
All you need is installation instruction that you can get through Google and you suddenly have a computer with new hard disk.
I upgraded from 160GB to 500GB and now have a computer with faster hard disk and loads of space.
PS
You need to be a bit technically savvy to do it and if you think you are then don't forget to lay the screws you are taking out of the computer on a similar pattern to computer on the table so you won't get them mixed!
If you haven't done it then you need to find someone who has!