I am going to buy an iphone 4 when it comes out and i am going to jailbreak my iphone 3g. I was thinking about it and i could just jailbreak it now, right? when i get my iphone 4 i want all of my stuff (apps, pictures, music, app data, etc.) to be on it but i don't want it to be jailbroken. can i still do this if i jailbreak my 3g now? also, i have OS 3.1.3 would spirit be the best option for jailbreaking?