Building a site with 2 languages - SEO implications?

Hey all,

I have this local business site created, all in english, all SEO'd and stuff, ranking well, all is good.

Now. Upon doing more in-depth keyword research, I realized that the french versions of the keywords are QUADRUPLE in terms of traffic.

Obviously, I'm scrambling to get this done today, but I'm faced with a pretty big problem: How the heck do I organize the file structure?

I thought of plugins to translate, but I don't think they do such a great job, nor do they translate actual content and I think the SEO would be pretty messed up, so I don't want to go that route.

The other thing I thought of doing is, and this is all Wordpress based, I was thinking of creating a new folder on my host next to all the WP stuff currently is, named "FR" , and copy the WP install entirely and tweak it.

I could also just re-install WP there with tables with a fr prefix, but I want to keep the SEO work that was done on the primary domain. I could be wrong here too where it may not even matter in the end, but I want the french pages to rank well too.

- OR -

I could just keep the site as-is, create a http://www.website.com/fr/index.html and use one static french page.


Anyway, I think you get the idea. Any feedback is appreciated, thanks guys!