How do I Make search results only show data from posts?

Hi I use wordpress 2.51 and I have a search option on my right side bar. I was wondering how to make it so when a user searches it only returns data from posts, and not from pages as well.

<form method=”get” action=”<?php echo $PHP_SELF; ?>”>

<input type=”text” name=”s” id=”search” size=”40″ />

<input type=”submit” name=”submit” value=”<?php _e(‘Search’); ?>” />

</form>

Any help would be greatly appreciated. My site is vandalizedmusic.com if you need it.

Thanks,
Tristan