I've only used the beta version and I had no problems with it, other then when I'd save something in .docx and need to open it on my other computer without the 2007 beta version and I was screwed
But you can save to the older format in 2007. I just bought the full 2007 version through school (only $55 for Pro) so I'm hoping it is just as good, hopefully better than the betas.
I'd look into using Exchange for e-mail. And I have never met a single person who didn't like gmail. Wouldn't hurt to at least look into it. I think it'd be great for business.