While you are trying to install MS SQL Server 2008 on the machine which already has Visual studio, you might come up with this problem.
Here is the remedy.
Go to command prompt and move to the MS SQL Server installation DVD like:
C:…>E: – assuming your DVD drive letter is ‘E’
Then provide the following command:
SETUP /action=install /skiprules=vsshellinstalledrule
While you are installing, you might come up with error message but pass it selecting ok.
The other solution might be the trivial one – uninstall VS and install MS SQL Server then install VS – 
I hope it will help a lot.