Robots.txt question...?

I just found out that Yahoo search is pulling up pages that I dont want it to. I created a robots.txt file that disallows all inside directories, everything but the main page. But I ran a search and the files are still coming up, how long does it take to take effect?
Here's the file:

User-Agent: *
Disallow: /content/
Disallow: /icontact/
Disallow: /images/
Disallow: /logs/
Disallow: /myspace/
Disallow: /tmp/