Boot Camp-Assistent!

Hi and thanks for reading what im about to tell you.

I'we got a problem by installing windows 7 ultimate from usb with Bootcamp and my problem is that when iwe done partionating it searches for a windows install disk or Iso image or something like that And iwe got my usb plugged in my Windows 7 ultimate.iso in the usb but bootcamp cant find a windows 7 install disk ?

iwe also checked so it is a Dos Fat ..

I'we seen people with like MacBook Air and other macbooks have a windows where it says " Create a windows 7 install disk " but iwe dont have one of those and its hard for me to get a regular cd or even burn it to a cd or dvd ...

please help my system is

2,4 GHz intel core 2 Duo

2 GB 1067 MHz DDR3

NVIDIA GeForce 320M 256 MB

OS X lion 1.7.5

Macintosh HD