Here’s a screenshot:
In the 2008 , they have added a new option to prevent saving of changes that will require a table re-creation. If you think about it, this is a good thing. If you are running a production database, you want maximum performance. If Management Studio needs to re-create a table to apply a change that means it needs to create a copy of the table, transfer the data, create the new table, move the data over, delete the old stuff, etc. This can potentially be a major operation.
However, if you don’t want this feature enabled or our just working with a development or test database, it is easy to turn off. Just open up the Options window in Management Studio and go to “Designers –> "Table and Database Designers”, find the “Prevent saving changes that require table re-creation” option, and turn it off.