I have a WD 500GB external drive. I generally use it for an extra back up. My main drive's are 2 WD 1TB in RAID 1 array.
I guess the need for an external drive will be determined by how much you need to store. You can get 64GB USB drives for 30 bucks these days and that may be enough.
Glock G19, 21, 22, 23, 26
Donít respond to the stupidity of a fool; youíll only look foolish yourself. Proverbs 26:4