Costing of email system

I’m currently doing a case study for college where I’m looking at implementing an email system for 350 hospital staff.

When looking into the following I’ve found the prices roughly to be:

1 x 699 = 699 (Exchange Server 2007 Standard Edition)

350 x 67 = 23,450 (Exchange Server 2007 Standard CAL)

Total Cost = $24,149

(Outlook is bundled with the pc’s im getting)

And

Domino Messaging Express = 102 x 350 = $35,700

Does this seem right??

I’m also not too sure if I Domino Express covers all my needs (Client/Server side) or do I have to get notes aswell??