How CNAME configuration is done varies from provider to provider. You'll probably need to delete the A-record for www, too.

And that's it! Once the DNS changes have propagated, which might take a few hours, visitors to your Website will be directed straight to the S3 bucket containing your site and will see the index.html file.

As an additional step, it's a good idea to point the A-record address (that is, the address without the www prefix) to a simple hosting service where you can set up an automated redirect to the www address.

If yours is a high traffic site, it might also make sense to use Amazon's CloudFront service to ensure traffic is directed to the nearest geographical server, which will avoid any latency issues. This will add to the costs, though.

So how does using S3 compare in terms of costs to a standard provider? I use Dreamhost's basic Web hosting package for the sites I run, which costs me $119 per year and offers unlimited bandwidth and storage (although I share a server with others, which can often limit the speed at which my site is served).