SEO issue with changing site from html to php

I am trying to figure out what way would be best for SEO for me to switch my site from html to wordpress, joomla or some other php script. It would make the site more functionable.

Problem is i am saturated with certain keywords in google and it makes me some money poker sales, and dont want to mess up the keywords. It is the site in my signature.

Should I leave it the way it is? Completely redesign and build for better functionality? Or maybe just integrate scripts into the html and use both?

I didn’t check the site, no time at the moment. Personally, I’d rebuilt the site from the ground up using Wordpress or Drupal depending on the functionality you need - I dislike Joomla for various reasons.

You then have various options: