Its not a dumb question, but you need to do some more reading here on these forums.
You definitely need to redirect the no-www URL to the with-www one ( or vice-versa, but be consistent! I prefer www.) This is a "301 redirect" best done in your .htaccess file. Google for webmasterworld + 301 + redirect + www . -Larry
This question is asked every day (indeed I have just answered the exact same question in another thread in this forum), and the correct thing to do is to use a 301 redirect. Instuctions for both Apache and Windows servers are readily available.