For a few months now people have been implying that SQL 2005 is just a feature release over SQL 2000 with no performance gains
http://www.eweek.com/article2/0,1759,1776014,00.asp
I was concerned that this may be the case too, when I asked an MS employee around 6 months ago he stated that they were aiming for performance within 10% of 2000.
Last week Microsoft revealed that 2005 had set a new TPC-C record, breaking through the 1 million barrier
http://www.microsoft.com/presspass/press/2005/jun05/TechEd2005Day2PR.mspx
They go on to state that this result is 38% higher than SQL 2000 and also higher than Oracle on an HP integrity Superdome.
The TPC results can be seen here
http://www.tpc.org/tpcc/results/tpcc_perf_results.asp?resulttype=noncluster
with the 2005 executive summary below
Comparing this to the SQL 2000 result
revelas that the 2005 is using twice the memory and faster processors. It would be useful to see a "like for like" comparison to see how much of the improvement is due to the new database.
The Oracle result was posted over a year ago - it would be interesting to see how it compares on newer hardware. Also note that Oracle is still ahead with a 1.6 million result on an IBM eServer.
Of course, for the majority of us, all this is immaterial as we will never be developing applications that requires hardware this powerful.