Deexgnome on "Query String / Month"

Hey,

i have a question to the query string. For the moment i use for posts
$my_query = new WP_Query('orderby=comment_count&showposts=3');

I have read http://codex.wordpress.org/Function_Reference/query_posts

but i'm not sure how to do it. What i would like to add is the command for yust display it for the comments of the current week.

I hope someone have a idea