Whenever I do a webcast or presentation, I always ask the audience to indicate where their organization is in relation to running SQL Server 2000 or running SQL 2005. Recently, in an audience of about 40 people, more than half of the audience still had more than 50% of their production servers running SQL Server 2000. One of the main bottlenecks are the vendors of third-party apps. This has forced businesses to choose their risk.
SQL Server Support Risk - The application will not run/be supported on SQL 2005 by the vendor. The decision has been made to keep the aaplication running and "hope" that there is no need for support from MSFT
Application Support Risk - The DB is upgraded by the customer (perhaps keeping the DB in '80' compatibility mode). The decision has been made to keep the data platform updated and under support from MSFT point of view while taking a chance of not getting support from the third-party vendor.
There are many factors that go into this type of decision. In fact, some organizations may choose to assume different types of risk for different applications/DBs. This is not a comfortable choice for any organization. Why don't vendors upgrade their DBs/Apps? SQL Server 2000 is a solid DB platform; 2005 is better. As time goes on, their will be more pressure for customers to avoid the SQL Server Support Risk (and associated costs). Customers will pressure the vendors to upgrade their DBs/Apps or lose a customer.
This now puts the risk on the vendors for not "keeping up". There is some advice for vendors who have not kept up.... Plan to Upgrade your DB/App to SQL 2005 now. While you are "under the hood", run the Upgrade Advisor for SQL Server 2008 and take care of that at the same time. This way, the application/DB will be ready when SQL Server 2008 is released and even more importantly when it becomes a standard/approved data platform for many organizations. Sticking with SQl Server 2000 may not have cost you business over the past couple of years, but it will cost you as the April 8, 2008 date gets smaller in the rearview mirror.