(adsbygoogle = window.adsbygoogle || []).push({}); So I have a 3GS on OS4, I am using Windows. What, if anything, is available to me?

I have searched but dont really understand it too much.

Can I downgrade to 3.1.3 and jailbreak using Spirit? If so how?

Or is there a working Jailbreak available to me?

+Rep for a good answer

this is what i did when i got the error.
1. Shift + Enter
2. Use 3.1.2 firmware first.
3. Once installed, you'll get the same error again.
4. Now, jailbreak using blackrain, since it's 3.1.2
5. After that, you will get no carrier, so you need to jailbreak again.
6. I used sn0wbreeze, since it let's you create your own firmware.
7. When using sn0wbreeze, it will create a custom 3.1.3 firmware.
8. Once done, now you can go back to itunes and restore with your custom 3.1.3 firmware.

It's a few steps, but it worked for me.