Accessing document.ready in drupal

Hey all,

I need to run some jQuery after the page loads because of a minor bug in a pre-packaged theme. Basically what I'm doing is replacing one class with another after the theme loads (the class is set dynamically in the pre-packaged theme but there's a bug I believe in the PHP part that it's putting in a typo). As a new member to the community, I will inform the programmer. But I have to do a quick fix in the next few days.

For the code development, I just placed the script at the bottom of the page but I want to place it in the document.ready but I think Drupal uses one already in the Drupal.js and that Drupal does something different.

Can anyone help?

Here's the code snippet.:

if (document.getElementById("menu_top")) {
$("#navigation > del").removeClass('move-');
$("#navigation > del").addClass('move-center');
}

Thanks