"Overnight success takes a long time"
If you plan to migrate to SQL Server 2008 or later in the future, you can save yourself a lot of trouble by being aware of the deprecated features. Some of the changes have been made to get in line with ANSI SQL standards.
MSDN has a detailed list of the Deprecated Database Engine Features in SQL Server 2008 and those planned for the future versions. T-SQL expert Itzik Ben-Gan has highlighted some of the more important ones among them & suggested best practices to follow.