Itzik Ben Gan's new one, SQL Server 2008 T-SQL Fundamentals. Almost all of it will be applicable to 2005. After you finish that one, pick up his older book Inside SQL Server 2005:T-SQL Querying. Those are two of the best reads on TSQL I'm aware of (especially since we're never going to see an update to the Guru's Guide to Transact-SQL).