As USAFRet said. Laptops, unfortunately, can have custom drivers to allow some specific components to work optimally.
On the other hand, W7 does come with numerous generic drivers. As long as you have the W8 install disks (in case anything goes wrong) - and back up what you need, then by all means, pop in your W7 install disk. I've had success with this type of scenario in the past. No guarantees though!