In general, yes. The majority of the time, SQL will only use one index per table for a query, if there are three conditions in the where and 3 single column indexes, it's likely going to use the most selective, then look up to the clustered index, then filter on the other two conditions.

I wrote a blog post about index columns. It doesn't cover exactly this question, but it might help.

http://sqlinthewild.co.za/index.php/2009/01/19/index-columns-selectivity-and-equality-predicates/