that's so funny, what makes you think i wouldn't??
just in case i made a phonecall to apple store on regent street in london today, one of the Genius told me that there should be no problem for a macbook to use retail version of tiger. unless they are very mistaken.
[updated]
Just received a call from the apple store, any one who lost their DVDs SHOULD contact apple care, then they will replace the DVD for you.