Of course the next thing you should worry about is stacking all the fixed length, non-nullable fields at the front of the page... There's a lot of things you can do to squeeze an extra MS or two out of storage & retrieval. Except, in very rare circumstances, they just don't matter to most systems.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning