How do I resize images?

Hi guys,

I am currently using the following method to display images in a loop:

<span class="company-logo">
<?php
	$company_logo = get_post_meta($post->ID, 'company_logo', true);
	$logo = wp_get_attachment_url( $company_logo['ID'], 'thumbnail' );

	# resize image before print

	echo( "<img src=\"$logo\"[0] width=\"250\" height=\"120\" />" );
?>
</span>

However the logo size is not constant throughout the output. I want the all the images to resize to a width of:
Width: 250px;
Height: 120px;