I'm installing windows 7 from a dvd, everything went fine but when i formatted the partition i wanted to install win 7 into, it says ''windows can't be installed on this disk. The selected disk is of the GPT partition style''. My computer has win 8 (64-bit), but I'm switching into win 7 (64-bit).
Windows 7 x64 supports booting to GPT disks. According to the TechNet article ‘Installing Windows to an EFI-Based computer’, you need to launch the Windows EFI Boot Loader on the Installation Disk. If you have the option to boot to EFI DVD, that’s what you need to do to get Windows 7 X64 to install on a GPT disk. The alternative is, as Ramhound suggests, delete all partitions and install normally which will format the disk as MBR.
Hope this helps,