Those 2 Articles have changed my life as a webdesigner a bit (well, in fact, ALA did). Those approaches to rounded corners are fine, still I developed another one to circumvent the inconvenience of either a giant topleft-image, and/or a box whose size is restricted to the background-images size.
As was mentioned here before, this forces me to expand the structure to 10 elements (a container box, a left, middle and right box for the top, center, and bottom part), plus the inner markup.
Although not so elegant in matters of markup and semantic, I now have real fluid boxes which can expand right up to mars. And transparency and dropshadows for png-supporting browsers…
To find back to easy-to-understand markup, I throw the whole box-stuff into a little script, thus all I have to do is give my container an ID and invoke the script who will do the rest.
(see it under development under www.d-ing.net - following pages)