After trying to get a decent connection speed using PPTP from StrongVPN I’ve decided to try with OpenVPN.
Currently I’m using StrongVPN to be able to watch Hulu and also to improve a bit the speed of my Internet connection (international link).
As StrongVPN doesn’t have on their website a step-by-step guide of how to configure OpenVPN in NetworkManager (they provide a shell script) I’ve decided to post three simple screenshot that can save you some time if you are confused. The only thing that you need to do is to download a file that they provide with the certificates.

Screenshots

Certificates File

Configure OpenVPN on Network Manager - Step 1

Configure OpenVPN on Network Manager - Step 2

Configure OpenVPN on Network Manager - Step 3

UPDATE:
It seems that there are already other guides: