>Some in our company are very very high on the Citrix/Metaframe concept, but others talk about the huge 'server farms' to support hundreds of users who might hit databases concurrently throughout the day...and recommend the more 'traditional' n-tier approach.
>

It is true that the power to run the servers is large - just think about what each user is getting when they log in. They are all getting a virtual NT session (I would allocate 50+mb RAM for each user).

You also need to research the cost of licenses... it is not a cheap solution AT ALL. For a Citrix site, you have to have (3) licenses... NT CAL, Terminal Server, and Citrix Metaframe. The last I checked, that's nearly $600/connection. And if you use SQL Server, you have to get a license for it as well.