I've played around quite a bit with link structure for various sites I've programmed. I've found that Google will index your pages whether they have a parameterized URLs:
or parameterized Paths (Permalinks):
I think, however, that in general, search engines like the path portion of the URL better than they like than the query string for indexing search terms. In addition, it makes the URLs easier to read and understand what the page is about.
Hint, for WordPress, you can change the link structure of your site on the options tab. If you change the permissions of the .htaccess file in the WordPress installation, it will even write that file for you. For me, WordPress is running under the apache user account.
>chgrp apache .htaccess
>chmod g+w .htaccess
>ls -la .htaccess
-rw-rw-r-- 1 root apache 204 Oct 1 09:12 .htaccess