I'm getting ready to sell my 2007 Macbook Pro (3,1 I think) and have run into a problem when I am trying to wipe my hard drive. I no longer have the original install disk that came with the computer. The only disk I have is a retail Snow Leopard disk. I tried to boot from this so that I could wipe the hd and reinstall OS X, but it keeps ejecting the DVD and not letting me. What can/should I do? The machine currently has Lion installed on it; will the internet recovery work? Thanks in advance guys.