4.0 jailbreak but I used Spirit last time!

[silvrwoman]

Okay, so I'm hoping someone can explain this to me in layman's terms, because I don't understand any of this:

I have an iPhone 3GS, software version 3.1.3 that I jailbroke using Spirit. I use a Mac OSX 10.5.8. I was thinking about upgrading to Apple's new iPhone 4.0 software, but I haven't yet because I'm confused about whether or not I can jailbreak it again.

1) The Dev-team's site says that PwnageTool 4.01 "only works on previously jailbroken 3GS devices with the old bootrom."
-->What is "bootroom," and how do I know what kind I have?

2) The site also says if "...you DID NOT use Spirit to jailbreak then you can create the ipsw with PwnageTool 4.0 and restore with your jailbroken recovery mode. "
--> I used Spirit to jailbreak 3.1.3 - is it still possible for me to jailbreak 4.0? If so, how?
--> What is an ipsw? Would this allow me to keep the apps/etc I obtained using Cydia? Or will I lose all of my info once I upgrade/jailbreak again?

3) Should I upgrade to 4.0 through iTunes? If so, should I do this before I jailbreak to 4.0 (if possible), or do I upgrade to 4.0 through the jailbreaking process?

4) In your opinion: Should I upgrade to 4.0?

Thank you so much. I know for most of you these are stupid questions, and I appreciate any help/advice given.

[Cer0]

1. The bootrom is the hardware that allows jailbreak exploits to run. When did you buy your phone?

2. It most likely you can't jailbreak 4.0. IPSW is the firmware file. Like the file iTunes uses to update the firmware.

3. If you fall into the new bootrom area then you cannot jailbreak being on 4.0 so if you want to stay jailbroken/unlocked then don't upgrade.

4. It is up to you on if you want to update. Do you need an unlock? If yes then for sure no. 4.0 added some nice features. It also added some security enhancments that safari had. But again you won't be jailbroken/unlocked.

[silvrwoman]

1. The bootrom is the hardware that allows jailbreak exploits to run. When did you buy your phone?

I bought it March 24 of this year. The model number is MC135LL if that means anything.

So basically, there's no way for me to jailbreak just because I used Spirit last time?

Thanks for the info by the way.

[Cer0]

You are on the new bootrom then. And yes there is no 4.0 jailbreak yet for the new bootrom. So you will have to wait for one to come out.

[derick]

I like the 3gs faster than 2g. I love me 2g cause it still unlocked but my 3gs just become a itouch