I am interested in getting a new iMac but have a few questions before I spend the big $$$. I am a high school teacher and use PowerPoint and Word everyday. Will I have any problems opening the presentations I have already made (on my PC) on the new mac? Or any problems making presentations on the mac and opening them on the Windows XP at school? This is my MAJOR concern! Would you recommend iWork '08 instead of Office? I also plan to use it a little for building a website, photos, and the internet; so will I notice a difference between the 2.0ghz vs. the 2.4? 1gb ram vs. 2gb?