Blogger to Wordpress - Archive Permalinks

I'm migrating to Wordpress from Blogger ftp, anyone know how to change the structure of Wordpress archives pages. I want them to match with Blogger like did with my posts permalinks.

Blogger
/2010_09_01_archive.html

Wordpress
/2010/07/

thanks, this is my first post glad to have found this community hope to be posting more.

you probably have to do a custom mod_rewrite to direct any existing links you have that point to the blogger style archive structure.