Transitiong exchange 2007 to Exchange 2010 after updating the other servers before internet facing server

I have our main internet facing cas 2007 at our main sight. I had to add exchange 2010 servers to a couple of new facilities in remote sights but they are all connected. I'm now transitioning  our last,  but main 2007 exchange to a new box with exch 2010 (all 2008r2 OS).  I was fallowing  the articles to make the 2007 legacy.domain.com to work with exch 2010and then realized that won't work because I needed to upgrade this server first before the others.  I had already changed everything on 2007 to legacy.domain .com and the new 2010 to mail.domain.com.  Email seems to be working fine on the new server and I believe I can move everyone over to the new server that does not access email remotely ( smartphones, owa, etc) I assume then after movng all users over then  I just need to move all the remote users at the same time and change the ip to that of the old server and send connectors?  Am I missing anything.  Right now I have various users still on the old exch 07 getting the whole pop up box to log in to email, (mail.domain.com) so I'm guessing outlook anywhere is not configured correctly as all their outlooks are set to "connect using http" or the fact that I changed it to legacy.domain.com. Usually I just have to change their authentication to ntlm and they work okay.