I am purchasing a secondhand iPhone 3GS on OS 4.0 from a friend. He bought it in November of 2009, so I'm pretty sure it has the new bootrom. It's never been JB'd before. I've done some research, and it looks like since I don't have SHSH blobs for the old firmware it is impossible to JB with PwnageTool or other programs. Is jailbreakme the only option I have? My only concern is the security issue, but I heard that it plugs it upon installation. Also, as long as it's JB'd, unlocking won't be a problem, correct? I forgot to mention that I have no interest in upgrading the OS, or at least until I feel a little more comfortable playing with it Thanks in advance.