So I have a 1st. gen 8g iphone 2.1 FW. with ATT as my carrier. I just Jailbroke my phone with quickpwn. and after flashing my bootloader from Cydia everything works but when I put in my sim card from europe it reads it but then the "plug into itunes" screen shows up and says "different. SIM detected."

I feel like I'm really close and was hoping for advice.
Ideally I want to use ATT in the US but when I travel would like to put in a local different SIM card.
thanks in advance for the help.
PS when I used quickpwn I had my ATT SIM card in ..does that matter?