The 2008 version of SQL Server Management Studio (SSMS) has a new option that can save you a lot of pain. In the 2005 version, you could bring up a table in the designer, and make just about any schema change you wanted, and then click the Save button on the toolbar. SSMS would automatically generate Transact-SQL code to implement the change as it saw fit and then run that code, which could be very costly on a large or busy table.
For example, SSMS might want to create a new table, copy all of the data from the existing table into the new table, then rename the old and new tables. This was known as “table-recreation”, which could be very expensive on a 100 million row table.
Now, in the 2008 version of SSMS, you can set an option that will prevent SSMS from doing this. This will save a lot of DBAs from themselves!