well, I'm afraid that you have been thrown to the wolves to be honest.
Most of these steps have nothing to do with virtualization or vmware directly.
Setup a new Windows 2008 VM and then use Windows 2008 documented procedures to install a new Windows 2008 Domain controller into a Windows 2003 Forest
Once that is complete and you transfer all the roles off the Windows 2003 server (including FSMO, DHCP, DNS, etc) then you can demote the Windows 2003 server and you are then left with a Windows 2008 domain.
Next you need to migrate from Excange 2003 to Exchange 2010 (which you can build as a VM), however this isn't something done with a few clicks of a button and depending on the environment size take calculations, testing and experience.
Unless you are an strong intermediate to senior windows administrator both tasks above should not be accomplished without help (and at the very least, the setup of a test lab and practice).
Doesn't take much to screw up either task and render your environment useless.