I bought a 160 WD Passport drive on black Friday for $70 at BB. In and out in 15 min but that's another story. I swapped it into my MacBook and put the year old WD 120 into the case. The WD ran great and didn't have any problems with it. I just wanted more space. They also had a WD 250 for $150 but I went the cheap route. I have the 500 WD MyBook for backup at home and will use that for Time Machine when I get around to it.
What Drew said; I use several of them for rotating-off-site backup drives. I've recommended them to friends and clients and everyone's very happy with them.
And double what Drew said about the company that sells them, eh?