Hi:
If you are just using a plain windows 7 installation DVD or usb flash drive, try this and see if it works...
Download the drivers from this link below (first or second file listed -- 32 or 64 bit as applicable).
Extract the files onto a usb flash drive.
With the flash drive and W7 installation media plugged into the machine, boot from the W7 installation media.
After you select the install now option, select the Drive Options - Advanced menu, then select the Load Driver option.
You should now see the storage driver files listed.
If you check the box, it will only include the compatible driver.
Follow the prompts and hopefully, W7 should install.