yes, die does stop the executing of the script.
But on another note, when running mysql_query and running into problems, it would be much better to use
or die(mysql_error());
then
or die("query doesn't work");
The first error is MUCH more useful in discovering the problem than is the latter error message. The first one actually tells you what the problem is. The second one just outputs what you want. You can change the query to the 2nd one when your site goes live and it's all up and running.
Cgraz