Editing a Operation System

i was wonder how can you edit or modify a operation system.
there a lot of operation system that are edit just for gaming and looks.
i want to edit mine own for window 7 and window xp
Thanks.
Answer #1
Try nLite
http://www.nliteos.com/nlite.html
for 7, vLite
http://www.vlite.net/about.html
Answer #2
For XP…nlite…free…Download:
http://www.nliteos.com/download.html
Not sure about Windows 7…But you can try vlite…
Answer #3
thanks guys
Answer #4
i told me to download something and i did and it still not working for vlite