Microsoft SQL Server is in the Leaders quadrant for the Gartner Magic Quadrant for Data Warehousing! Read about it here Magic Quadrant for Data Warehouse Database Management Systems, 2007 or in the official announcement from Microsoft: Microsoft Is Positioned in Leaders Quadrant of Latest Magic Quadrant for Data Warehousing.

Add to that (source Jack Bradham's What's New in SQL Server 2008 for Developers Webcast ), speaking about SQL Server 2005:


 From product functionality we are continuing our leadership in security with a recent analyst report shows us that we are years ahead of Oracle in producing secure/reliable product. On the benchmarks – we are increasing the leaders the DW Benchmarket leader with the #1 Price/Performance Non Clustered Benchmark in the 3 TB range and #1 Performance Benchmark in the 1 TB range
In the application space – we have 9/ out of top 10 price performance benchmarks for TPC-C
We have also released the first TPC- E bechmarks which provide more realistic customer scenario and also negates the benefits of Oracle RAC

This has propelled SQL Server into impressive growth – We have shipped more units that Oracle and IBM combined.
Our growth is not only limited to DB but also to BI where we are the fastest growing BI vendor – among the top 10 vendors.

From a breadth perspective – we have had over 8million SQL Server Express downloads and have built an impressive ecosystem of partners trained and applications certified.