Please help! I can't figure out how to upgrade and jailbreak my 3g itouch?

I have a 3g 8gb (MC086LL) itouch that is jailbroken with 4.2.1 firmware and I have been using 2g firmware. The problem is for some apps that I have I need 4.3.3, but when I try to use shift restore with the sn0wbreeze jailbreak iTunes says: The iPod could not be restored because the firmware file is not compatible. Also for some reason if I try to update the software on iTunes, it tells me that 4.2.1 is the current version. I am really confused and any information or tips will help. Thanks!