Today I've been looking into what's involved in upgrading our Exchange 2007 server to 2010. At first this seems like a simple request, but it turns out it's actually incredibly complicated.
The main issue is that you can not perform an in-place server upgrade from 2007 to 2010. This really means you have to setup either a brand new server to host 2010, or set a temporary server for 2007, move everything over, remove 2007 and install 2010 on the existing server and move everything back.
For a small company this is a big deal, especially as you have to install on 64 bit hardware.
Also, our Exchange server is also our domain controller. Yes I know this is not recommended, but sometimes there is no alternative option.
Luckily I have a 64 bit VM server with a bit of spare capacity so it looks like I'll be spending a weekend setting up an Exchange server on there and doing a whole load of installing and uninstalling. Can't wait!