you don't need to restore it to factory state unless you are paranoid about data you put on there... then you could just delete what your worried about and do a Secure Empty Trash... let Apple worry about it, because if you waste your time wiping and reinstalling the OS, they'll just do it again anyways.
If you really want, you can hold down Opt when you turn it on from the time you hear the chime, and let it up once you see the boot menu. Boot to the Lion recovery partition, and you can go in there and use disk utility to wipe the OS partition and do a fresh install of the OS. When the install gets to the part when it starts asking about adding a new user and stuff like you saw when you first turned it on, just turn it off there.