I would like to buy the box set as i need Ilife 09 and Iworks 09. I already have leopard installed. I understand that the box set comes with 3 separate DVDs. Stupid question i guess but i dont want to install my OS again. I assume its ok just to use the ilife dvd and the iworks dvd and not use the leopard dvd.In other words all 3 dont have to be loaded at the same time?