dahowlett - If you're interested in using charts and Excel information in web portals, that will be possible with Excel Services in Office 2007. You may want to watch some of my earlier Channel 9 video, and look at some of the Excel Services posts on the Excel blog to learn more.
TrayJoe - If I look sleepy it's because of the 5 month old boy and 2.5 year old girl at home.
ohgood - Looks like you've gotten some replies on your post already. There are new file formats for Office 2007, but they will be fully documented and open XML. I'm sure other products that read Office 2003 files will add support for these new formats in no time. Plus, people will still be able to save files in the older formats. If you have more quesitons, you might follow up Brian Jones (at his Office 2007 file format blog: http://blogs.msdn.com/brian_jones/).
Andretzu and Simo - We're being very careful about backward compatability with older versions of Excel. For answers to these specific questions, you may want to ask David Gainer (at his Excel 2007 blog: http://blogs.msdn.com/excel/)
- Mike Arcuri