Custom Field in wp_query

Hi there.

I have a page template that I am also using to display some posts. So – for example, a portfolio page, where I want to display the_content and then below that I would like to display some posts from a category.

No problems there. I can do that through a page template. Here’s the part I can’t work out:

I would like the person who creates the page to choose which category the posts come from. So. I was wandering – is there a way of setting up a custom field in a page (say “featured_category”) and then use that custom field in the wp_query that displays the posts?

So something along the lines of

<?php $recent = new WP_Query("category_name=$key&showposts=3"); while($recent->have_posts()) : $recent->the_post();?>

But I’d need to pull the $key from the custom field of the page that is using the template.

Thanks for your time.
Andy