He wants external.
As long as your PC has a free USB 2 Port, USB can do around 40mb/sec which isn't bad. External hard drives are much of a muchness to be honest, just go for a well known brand

In the long run, if it's speed and reliability you're looking for then an internal drive is the way to go, but at the end of the day, this is down to whether you want to move the drive around or not.