SELECT Statements only please I have a user that wants to use SQL Server Management Studio (SSMS) to run SELECT statements.  I don't want him to be able to modify data.  

I can't regulate his permissions through Windows Authentication because his user account needs modify permissions for programs that we run.

I could create a separate Windows account for him with less permissions, however if he does not use this new account, he will be able to change data.

Does anyone else have this problem? Is there a simple solution?
Grant the user read-only access and have your programs authenticate as a different user (one that's got modify rights).