About the Office 2007 vs. the Mac versions. I personally like Office 2007 (on Windows) FAR better than the Mac versions of Office, especially the last 2008 thing. That is a mish-mash of interfaces of the worst frankenstein result, imo. They couldn't go full-on with the ribbon, so it ended up really, really weird and incoherent.
The ribbon in 2007 is basically fantastic. It takes the best parts of the pallete that MBU created and makes it far more usable in practice. IMO, best innovation to come from Microsoft in a long time. (Why the weird circle Office button, though? Ugh.)
Now, the problem with the ribbon is the adjustment period. If you are really diehard into the older methods you'll likely resist everything and make it painful for yourself. I teach classes using Office 2007 and I find it to be much more intuitive and graspable than the older stuff, especially for new users.
IMO Office:mac 2008 got it pretty well right with what you can turn on and off *customisation! Definitely not something that Apple is likely to provide, and as it turns out, Microsoft are trending away from such themselves, hence no preferences for the ribbon in 2007. It decides what to show you, and leaves a huge amount to be desired. At least the fact that keyboard shortcuts from 2003 still work means one can still find things, whereas I've been using 2007 for work for about a year and only just found out the other way to bring up the font dialog, paragraph dialog, and styles pane ... a tiny glyph at the bottom right of the ribbon areas, so inferior to choosing options from a menu that I couldn't begin to describe.
Anyway, for instance with Word:mac 2008, you can set custom keyboard shortcuts to your heart's content, modify the menus themselves, hide the toolbar completely, as well as the sections of the formatting palette that you don't want to see appear, and you end up with a highly tailored interface that actually works quite well. There is a lot in the Ribbon that I would hide and change in the ribbon in the 2007 apps *just being able to have it vertical on the side à la the formatting palette would be great and save that valuable vertical screen real estate on a wide screen!
Back on iWork again, one big problem is that the apps disagree vehemently with their MS Office equivalents on how much content can fit on a page, with exactly the same margins and paper size. This means you can't rely on things looking the same on the Windows side with exports. Page and section breaks also tend to ... break in conversion. Anything with images becomes a nightmare to get looking good on both sides, and Pages just willy-nilly removes any content it doesn't like. I've just changed a 'text frame' to a 'text box' in a template from Word 2007, so that Pages doesn't just completely delete that content.
I have set up empty new documents for the iWork apps for creating Office-friendly files, and that helps a lot, and I guess once you learn the big problems, there is a lot you can avoid. Conveniently I'm pretty sure that will mean completely avoiding making graphs in Numbers ... boy is that a painful experience. Excel 2003 made the process pretty much foolproof. Excel 2007 made it so much harder I didn't think there was a beyond, until Numbers showed me the path

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