Windows 7 prefers to install to a raw unformatted hard drive partition. Disconnect all other hard drive other than the one you want to install Windows 7 on, set DVD drive as First Boot Device in the mobo BIOS and Save.
Reboot and let install begin, when you're at the Advanced Screen, delete all partitions and create about a 48-64 GB partition and let Windows 7 install to it. Don't format the partition, Windows 7 will do it automatically.