I am currently running MS SBS 2003 and have some XP machines (running Office 2003) and a few Windows 7 machines (runnng Office 2010). I am pretty green when it comes to IT on the server side (our previous IT manager left without warning, so I am trying to learn as I go) Anyway, we are looking to upgrade to MS Exchange Server 2010. My question is....is that the entire OS for the server (Exchange 2010) or just the part that manages our e-mail? I thnk it's just the e-mail part. I want to upgrade our Exchange, but our server is our domain controller and I don't want to mess with all of that if I don't have to. Also, if it is just the e-mail part, how would that effect all the people still running Office 2003? I know this is a crazy question, but I am confused about upgrading, don't want to screw up the network, but would like to upgrade exchange to a more modern version. Any thoughts or suggestions would be greatly appreciated. Thank you.