However, if you are feeling "collaborative" (to use an MS buzzword) and want to actually mail those files to other people, then it's a right pain. Assuming your correspondents don't have Office 2007 (and most of them won't), you'll either have to do a 'Save As' into the old format every time you send a file, or convince them to install a converter (and pray they're running a version where that's an option). Frankly, who needs the hassle?

Reason 4: You use macros and other customisation features extensively. Microsoft has always boasted about the fact that there's an entire community of Office developers out there building custom applications on top of Word, Excel and the like. It generally makes less noise about the fact that every new version of Office renders these inoperable until they're recoded to fit the new interface and file formats. With ribbons sprinkled everywhere and a totally new approach to files, there's no point even contemplating shifting unless your developer has already made the migration, or you have a lot of time on your hands.

Reason 5: It's still essentially a version 0 application. While Microsoft boasts that the number of beta testers for Office 2007 far exceeds any previous versions, it still remains a product that's only just come out of beta. Yes, it's selfish to let other people discover all the flaws, but why risk your business (or even just your home PC) until there's been a patch or two?
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