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#11
If you can, delete all partitions on the hard disk so that all space is unallocated. Later, you will be able to create any partition(s) using the Windows 7 DVD itself.
Are you sure you are booting from the DVD? Sometimes you need to go into the BIOS and make DVD the first boot device. Either that or press ESC or F10 key (it varies between systems) during the POST and you can choose the DVD.
If you have any IDE/PATA drives, make sure jumpers are set correctly.
Also, when you write an ISO to DVD, you need to burn it as an image so it will be bootable. If you wrote the .iso as a file to the disc it will not work (i.e. if you put the disc in another computer and you see an .iso file on it, it is in the wrong format).