Adding a new hard drive

[revloc8]

I built my own computer no probs, but now I wanna add a new HDD. I currently have a SATA Barracuda 7200.9 80gb drive, but its a lil small. So Ill prolly get a 400gb+ drive for Christmas. Anyways, my question is this: Can I just plug in the power and SATA connector and go? What I would like to do is transfer my data files to the new, bigger drive and then reformat the 80gb one and use it solely for os, programs, etc. Whats the easiest, safest way to do this? Thanks in advance.