Hi Shari,
I downloaded a wordpress plugin that blocks spam. It's called
Akismet. Which can be found here
http://.codex.wordpress.org/Akismet
I love Akismet. No spam problems at all!
Another wordpress spam plugin that others swear by is call
Spam Karma 2. Which can be found here
http://unknowngenius.com/blog/wordpress/spam-karma/.
I tried Spam Karma 2, but did not like it because it was marking legitimate posts as spam. It blocks spam based on your requirements.
One of these plugins should help you.