Duplicate page penalty

[OSCC]

Google has apparently decided that since I my pages show up as both http://www.mysite.com
http://mysite.com that I have duplicate pages and has killed my site. I used to be in the top five but now I am not in the top 300.
Where can I get help on using my htaccess file to force all requests for http://mysite.com to put http://www.mysite.com in the url box?
I cannot use mod rewrite, the site crashs.
Here is my htaccess
ErrorDocument 404 /page_not_found.htm
ErrorDocument 403 /page_image_ forbidden.htm
SetEnvIfNoCase Referer "^http://www.mysite.com/" locally_linked=1
SetEnvIfNoCase Referer "^http://www.mysite.com$" locally_linked=1
SetEnvIfNoCase Referer "^http://mysite.com/" locally_linked=1
SetEnvIfNoCase Referer "^http://mysite.com$" locally_linked=1
SetEnvIfNoCase Referer "^$" locally_linked=1
<FilesMatch "\.(gif|png|jpe?g)$">
Order Allow,Deny
Allow from env=locally_linked
</FilesMatch>

[firepages]

Google will not penalise you for this alone , if someone told you otherwise , slap them.
Your problem is elsewhere.

[mlseim]

I've noticed that when Google first ranks a new site,
one that it has not been indexed yet, it seems to put
it at the top ... as if to give you the benefit of the
doubt.

As nobody clicks on it, or no other sites are linked
to it, the site quickly slides down.

Popularity, and other sites linking to yours, seems
to be the biggest factor in ranking.

.... just my opinion.