I guess I didn't explain it well OR i didn't understood your problem.
After the windows "dos installation" your pc will come to the point where it says that your pc is about to restart in aprox. 10 sec (The red Loading Bar which is counting backwards). When you see this take out your Windows cd from your Drive and let it out. Your PC will restart.
Now since there is no Windows CD in your Drive, Windows will not start again the "dos installation" instaed Windows will boot into GUI mode since it cant boot from your CD.
(At this point windows cant loop back to DOS installation, to do so it would need to read the windows cd, but there is no CD, got it? )
Now after some seconds in gui installation windows will notify you that there is no CD in your Drive.
At this point just put the Windows CD back again and press Ok or Continue or Browse and navigate the CD/DVD Drive where your Windows CD is and press ok.
After this windows should finish the installation like normal.