I have an iPhone 3g that I successfully jailbroke using redsn0w. I installed the repository for ultrasn0w, and now I want to jailbreak it for t-mobile. I have an iPhone AT&T SIM card also. I know that I should disable 3G before installing ultrasn0w with my AT&T SIM card. After installing ultrasn0w and turning the phone off for a hard reboot, do I take out the AT&T card and replace it with the t-mobile SIM? Or do I reboot with the AT&T card in still?