Western Digital caviar green/black 2TB for External?

Hello there,
I want to purchase a hard drive and put it into external enclosure and basically use it as such. I know the WD caviar Black has MUCH better performance, than the Green, series, but also the Green generates less heat and makes less noise. My main reason to consider the black as an option to put it into external enclosure is, that it still offers 5 year warranty, which might mean it is expected to last longer. I have a Hitachi 160GB, whch soon will make 8 Years of service (not 100% uptime, but still...). Apart from several bad sectors I didn't experience any problems with it. I also have a 500GB Samsung, for which I can't say awesome things, so I will be avoiding this brand for now.
What's your opinion? Is it worth it to put a Caviar black in external exclosure, or just purchase retail WD external HDD, which most likely packs Caviar Green?
Thank you!