When putting forth a recommendation for a version and edition of SQL Server to install it is important that you understand what features are available in each version and edition.
SQL 2000 – http://msdn.microsoft.com/en-us/library/aa175266.aspx
SQL 2005 – http://msdn.microsoft.com/en-us/library/ms143761(SQL.90).aspx
SQL 2008 – http://msdn.microsoft.com/en-us/library/cc645993.aspx
These 3 websites give you a very detailed look into each version and edition of SQL Server and the features avaliable for each. It always easiest to recommend the newest and hottest for your customers but without evaluating their needs and cross referencing that with the feature lists above they may be spending more money then they need.
(that being said I don’t think recommending a SQL Server 2000 solution would be a great idea either 
hehehe )
