Also, Kyls writes:
"I wish there was an option to tell SQL Server "No matter what, never table scan a table with more than a million rows; if you come up with a plan that does that, punt and throw an error message instead, so a DBA can fix it, rather than pound on a production database for 10 minutes straight"
to which Darrel Responds:
"Kyle, there is something similar to what you are asking for. Check out the Query Governor Cost Limit Option for SQL Server configuration: (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/adminsql/ad_config_73u6.asp). "