I prepared a bootable USB from the Windows 7 install DVD using Wintoflash. When I inserted the USB and launch boot camp assistant to click "continue", a message popped up saying something like "this computer need 64bit Windows install disk". ls it because my install disk is 32bit Windows & and my iMac late 2013 does not support? I did not even get the screen where I can slide around to allocate space for my boot camp Windows. Is this normal? Thanks for any advice!