Sounds too good to be true does'nt it?
Microsoft have just released some test results that compare the performance of SharePoint Portal Server 2003 on SQL 2000 vs. SQL 2005.
Using SQL 2005 improves performance on every type of SharePoint farm configuration, but the most notable is a 51% increase in RPS (Requests Per Second) for a medium server farm under SQL 2005. The full table is:
You can get to the full test here: http://office.microsoft.com/en-us/assistance/HA100993571033.aspx