Exchange 2007 / 2010

Check this link http://technet.microsoft.com/en-us/library/dd638158%28v=exchg.141%29.aspx

It provides all the information you need for upgrade and coexistence.

Thanks.

I've read the document, however this doesn't seem to describe our scenario unless I'm missing something.

The only reason we want to introduce Exchange 2010 is so we can support an O365 hybrid setup. We thought you could just introduce the new server and sit alongside the existing 2007 server. We'd would eventually want to decommission the 2007, however for the initial hybrid setup we wanted to maintain as much of the infrastructure as it is.

So, can you install Exchange 2010 and not transfer the roles from 2007, at least in the short term?

I don't think you need to transfer any role, only change might be if you want to use your old OWA url to access exchange 2010 OWA, you need to rename old URL.

 Try this deployment assistant, it will show you prerequisites and steps involved.
http://technet.microsoft.com/en-us/exdeploy2013/Checklist?state=2284-W-AAAAAAAAQAAAAAEAAAAAAA~~#Index

http://technet.microsoft.com/en-us/library/hh852414.aspx

OK, I've had a look through the docs, but I still cannot see any definitive answer to the question whether I can simply add an Exchange 2010 (SP3) / 2013 server with just the CAS role (as required by the hybrid solution) and leave the Exchange 2007 server roles exactly as they are.