Ok so i bought a copy of tiger dvd off ebay for like 25 bucks and it comes with everything i needed...for my emac now will it erase everything on my mac...i really dont want to have to install office mac, adobe creative suite 2, dreamweaver, flash, fireworks etc....is there a way to just upgrade? and how much disk space will the new tiger take? and does it have itunes, iphoto, imovie, garageband installed? or do i have to buy that? my mac now has imovie and iphoto thats it!