Switching from Win8 to Win7 will replace Win8 on your HDD so follow the instructions to backup your current system (1xDVD, 1x16GB USB stick).
All the information is available on the forum in a number of excellent posts - perform a search and read all you can find before you do anything! There are a few 'Gotcha's' you will need to watch for but, as I say, all the info you need is here.
Own a Predator Laptop? Then I bet you have learned a thing or two from beststevie. He has been helping out in this forum for quite a while and it's about time we recognized him for it. Thanks beststevie!