iPhone iPhone 3G 4.2.1 stuck on emergency screen

So yesterday I got an used iPhone 3 as a gift, but it was so full of useless crap I simply hit the reset everything options in Settings.

Big mistake.

After hours of tweaking, I was able to get it up and running, mobile signal and all, but at 3.1.3 version. Since a lot of the apps I wanted required a newer iOS, I just went ahead and used iTunes to flash it to 4.2.1.

Another big mistake.

Long story short, I'm now at 4.2.1 and stuck at the Emergency Call screen. How can I get out of this mess?

 

But which IPSW should I feed to it? It gives me "Unable to recognize specefied IPSW" when I input the 4.2.1 IPSW into it.

 

But it is restored... I think. There is no restore button on iTunes, only that "sim card not supported" message.

It seems I was using a slightly outdated version of redsn0w. (i lol'd when I saw your avatar on my iPhone screen). Seems to have worked, thanks! Now I just need to get my mobile data working...

 

Hmmm.... Well, nonetheless, how can I tell if my phone is jailbroken? I have Cydia, and am now installing the ultrasn0w repo (so I can make calls and stuff again); does having Cydia indicate that it is jailbroken?

EDIT: Ok, but how on earth am I supposed to use this if every useful app either requires open gl 2.0 or, worse, iOS 4.3? Any help making apps like Facebook work?

 

Turns out ultrasn0w did the trick just fine, I'm making calls and all.

Well, guess I'll have to make do with what I got... But even Facebook doesn't work, dammit @_@