Well, I think this comparison should be made in terms of cost of ownership for let's say 5 years. I was trying to compare Exchange vs GroupWise for 5 years, and I couldn't get the Novell price below the Microsoft one. Even more, with my calculation I got the Microsoft solution about 4 times cheaper for 500 users !?!? I'm not a Microsoft engineer, and most probably I didn't calculate all the necessary licenses, etc. from MS, but I hope more people will start calculating and we will end up with the actual comparison between the two.

So, let's define the following scenario:

New organization, no existing servers.
500 Users in one building, respectively one LAN
Needed services - DNS, DHCP, File Storage, Print Service, Directory Service, Collaboration System (don't know if MS has a competitor for ZCM, but if it has - feel free to include it). Server hardware kept to minimum (there's a financial crisis you know).
5 years of updates (don't need new versions, don't need support, but you may add it on separate lines anyway for the comparison to be complete)

I'm curious to see what will be the outcome of this.

Happy calculating!