hi i've been wanting to reformat my pc for a while and i've looked on the net fior a few days now and i can't find what i need, i dont have a windows cd or any other cd's with my pc, i've reformatted to factory default before by pressing one of the f keys and other stuff at the pre boot menu but i can't remember how to do it, its a dimension 3100c if someone could tell me what to do i would be so greatful. thanks in advance.