Upgrading from 3.1.3

[cowmang]

Hi I'm new to jailbreaking so I'm sorry if I'm using wrong terms. I have a 3.1.3 Iphone 3GS, with old bootom, that was jail broken using Spirit. I'm trying to upgrade to a newer version since mine is pretty outdated haha. My friend told me i could use "spirit2pwn" but i'd like a second opinion. The modern Firmware that my iphone shows is 05.12.01 if that is any help.

I'm running on Windows and i dont have access to a mac could someone help me please and thank you

[iYeow]

Do you need unlock? Download tiny umbrella and click save shsh after plugging in. Let us know what shsh blob you have.
Don't use spirit2pwn .

[cowmang]

I have a sim card so i wont need an unlock. The SHSH Blobs saved are 3.1, 3.1.2, 3.1.3, 4.0, 4.0.1, 4.0.2, 4.1, 4.2.1

[iYeow]

What firmware would you like.

[cowmang]

I was hoping to upgrade to 4.0, unless one of the newer versions run better on the 3gs.

[iYeow]

You can go to eitherr 4.1 or 4.2.1.
If you want 4.1, then download 4.1 fw and make sure you update your itunes to the latest.
Run itunes , and shift + restore to 4.1 ipsw.
Jailbreak with Limera1n or GreenPoison.

If you shift + restore to 4.2.1, then jailbreak it with redsn0w 0.9.6b6 and just check install Cydia, boot images, recovery images if you like.

[cowmang]

okay that sounds simple enough, but does the fw have to be custom made or can i just download it from the the "[How-To] Using tiny umbrella to update/restore" thread

[iYeow]

You use tiny umbrella to help you verify 4.1 shsh blob if you plan to restore to 4.1 thru itunes. If you are restoring to 4.2.1, you don't need the help of TU to help you verify as Apple is now signing 4.2.1

[cowmang]

okay thank you for the help