Although I'm not a huge fan of Windows, Exchange, and the like, I am a huge supporter (although not current a user - was a SQL Server DBA for a few years) of SQL Server. It is probably Microsoft's finest engineering product. Not only is it a super reliable and scalable system T-SQL is actually a user-friendly SQL dialect, and SQL Server Enterprise Manager (or whatever it's called today) is very user-friendly, too.

Although I'm a true-blue PostgreSQL believer, I give major props to the SQL Server team. In comparison, Oracle is a disaster (I was reluctant/forced Oracle 8i/9i DBA, too).