Pre-JB Research

[liquidzoo]

Here's what I have:

iPhone 3GS 32GB with iOS 4.2.1, bought at the end of July but I'm not sure if it's the old or new boot rom. I've googled, and I've found a way to tell, just waiting until I'm ready to do this to try.

I have the newest redsn0w beta. I'm running Windows 7, so I know I need to run it in compatibility mode for xp sp2.

So...now what? I'm fairly certain that I want to Jailbreak, but I'm not sure of what precautions I need. I was jailbroken before using jailbreakme.com, but I upgraded my iOS hoping for battery life improvements that I haven't been able to fully actualize.

I know that I need to plug in my phone and follow the instructions on redsn0w, which I have read on the net. My guess is that it will be a tethered jailbreak, but I've read that it might be untethered depending on the boot rom, right?

Are there any stand out issues that I would need to know about? I'm away from my home computer for at least 10 hours a day, and I use my phone for everything from audiobooks during my commute to music and podcasts while I'm at work and texts back and forth all day. I really couldn't afford to have my phone crash on me and need to be tethered in order to boot back up... That's the one point that's holding me back.

[i.Annie]

You seem to have gotten it all down. Old bootrom=untethered and new boot=tethered. For 4.2.1, just be sure you have at least the Redsn0w 0.9.6b6. I can't be sure but the I think rc versions are for beta firmwares only. b6 will work well though.

If it is new boot you should think twice if you can't afford for it to reboot and get stuck.

[liquidzoo]

I have whatever the newest redsn0w is (b8, I think) and yes, I'm going to check the bootrom version before I do anything.

Crossing my fingers for an old boot rom, but I honestly have no idea.

[i.Annie]

it's rc8. you'll probably want b6.