you have numerous SEO add-ons for joomla... That will not be problem if you want to use this CMS... You 'only' need good idea for site and good links...
I haven't used Joomla yet and read in the past peoples concerns of it being SEO friendly or not, a while has passed and it seems to be less and less of a problem/concern now. I will be using Joomla myself soon, for the first time, im happy theres so much available for it.