Well, there are a few options.

First - we need to know if your Scart handles a VGA signal and maybe a few technical details about the TV (is it PAL is a good start). Most likely the most cost effective is to buy a new TV - however, from a technical standpoint there are two things worth looking at:

Your best bet is something from here:

http://www.js-technology.com/product_info.php?cPath=21&products_id=39

Pricy - but will do the job.

Or check out some posts from the likes of appletvhacks.com - I read about a guy this weekend that made his own cable to do this - unfortunately I'm at work and can't get to that page.... http://www.tuaw.com/2007/03/23/apple-tv-works-with-standard-square-tvs/ might also be of use.

Cut Price Cables have a Scart-Component adapter for a fiver (http://www.cutpricecables.co.uk/ look under SCART to RGB), assuming you have a SCART socket that is RGB enabled. You'll need some phono leads for the sound, though.