Many versions of tracking code

When I tried to use Website Optimizer, I found that it doesn't use already installed Google Analytics tracking code. It needs another one.
Now I've found that if you want to use Conversion Tracking in AdWords, you need to install a separate code too.
Help page says in a "Advanced tracking options" section:
The Google Analytics Tracking Code will not interfere with the AdWords Conversion Tracking code if you use them at the same time on your site.
But do I get additional value from Conversion Tracking if I already use Google Analytics? This is still unclear to me.