Yep - I setup Exchange 2003 easily - with a few pointers [and msexchange.org is awesome place to help you with guides and tutorials]
If you are used to Windows server and all the usual stuff like dns, dhcp, wins, etc etc etc - then you shouldnt have a problem setting it up either :)
btw each user/device cal allows that user/device to use Outlook Web Access [OWA] which is the webmail thing. You definately dont need a £10k thing. I know what that thing is tho - its some sort of site license covering you on the cals front [i remember the company i rang for another quote saying about it] - it most certainly isnt needed or required tho.