By original do you mean the first HD Hero?
If you go for a new GoPro definitely go the Black. The Silver and White and just GoPro HD Hero2's in new casing, so no major recording quality upgrades from the last generation - although it'll still be an upgrade for you since the original Hero's were a decent step below the Hero2.
The Hero3 Black is a different story though - definitely worth a good look since it records at 60fps at 1080p.
Picture quality on the Black is amazing, only downside is short battery life (bout 1 and a half hours on slope recording at 1080 / 60 fps).