hello, my problem is the following, i received my copy of windows 7 proffesional this morning and i let my sister do the installation while i was at work...she by mistake installed the 32 version and not the 64 bit one. When i enter the dvd with the 64 bit version of windows to start installing the 64bit version i get a message that says this operating system cannot use the software and i must use the windows installation disk (i didn;t receive anything like that only 2 dvds of 32bit and 64bit versions) and choose custom advanced installation from there... what can i do ? what is this installation disk of windows 7? I tried rebooting the pc using as first bootable device the cd-dvd rom while i had the windows 7 64bit version in and nothing happened. thank you.