Well, IF Your Htaccess commandlines are right, And You have Saved it as .htacces, It Will Force the URLS To Act up on! ~ExP~
If you're htaccess file has been renamed to .htaccess, then you need to turn on Joomla's SEF feature. You can do this in the Global Configurations menu, under the "Site" tab, in the SEO Settings area. Make sure to check both SEF URL's and "Use Apache mod_rewrite".