It would ultimately depend on the company's requirements, and how willing they are to get there. For example, is this company willing to send someone from the IT department to train on SQL 2005?
As for the benefits, the one benefit all applications will derive is that SQL 2005 is generally faster than SQL 2000. You can't put a real factor of speed increase on it, but I have seen up to 4 times faster on the same hardware. That could be because I am lucky when I pick my examples, though.
If you are willing to put development effort into an application, you can get built-in encryption for sensitive data, built-in partitioning for large sets of data, or any of the bolt-on applications Microsoft is pushing with the SQL Licenses these days (Reporting Services, Notification Services, Analysis Services, or Integration Services). Outside of that, you would have to look at and probably test your application on 2005 to see what you get out of it.
Also MS weblinks for more information (though they talk more about their product) http://www.microsoft.com/sql/prodinf...s/default.mspx http://www.microsoft.com/sql/downloa...-software.mspx
1. SQL Server Integration Services is the new version of DTS. It is a complete rewrite of the product rather than an upgrade and will put give MS an ETL tool on an equal footing with the big ETL players.
2. Analysis Services has been completely re-architected to include (such as) multiple hierarchies in a dimension, KPIs, perspectives, and many other things all hosted in a new conceptual object called the Unified Dimensional Model (UDM).
3. CLR Integration - Stored procedures/functions can now be written in a .Net language.
4. Table partitioning improvements
5. Reporting Services enhancements
... for more list of features refer to above links.