Installing Custom Files with the OS?

When you install some certain Os, it comes with no drivers. I want to install for example the network drivers, video drivers and Easy BCD and VM or any other custom file that i choose. But i need to do this with the OS installing. I have seen some custom win 7 where ImgBurn and Mozilla firefox comes pre made with the OS. <---------- Rockers Team makes these Win 7s. But i would like to know how to install files that i need with the OS at the same time, so i dont have to go searching on the internent, when i probably wont even have the network drivers installed!. Please help me. Thank you!