Wintel / SQL Server environment for approx. 2000 users

I am currently on a team that supports mutliple Wintel servers and MS SQL Server databases. Our Openfire environment should not exceed more than 2000 users and is intergrated with Active Directory. Most if not all of the end users will use Pidgin as their IM client. Do you seen reason based on my teams skillset as to why we should select something other than a Wintel server and MS SQL Server database? Also, any insight related to

redundancy would be greatly appreciated.

Thanks for any help you can provide.