I just upgraded mine, was a pretty simple process. Hardest part was getting the freaking external case open to take the hard drive out. As far as recommendations, I've heard that Seagate drives make a lot of noise. Not sure if it's true or not, but I got a Samsung drive (in a Seagate case). This one:
http://www.amazon.com/gp/product/B00TKFEE5S
They go on sale a lot so you might want to wait till you see a sale