sorry i didn't really explain it very well, a better example is at http://www.faceparty.com the whole page is in a blob (round edge rectangle) and this blob changes length to accomatate how much text/images are inside it.
no, i'm trying to put the page content inside a rounded rectangle, but my site has lots of differnt pages and its updated a lot, so instead of having to change the height of the rectangle every time i add or take away suff from the site, it will just resize automatically, like faceparty's site does, and the corners need to be rounded.
yes, its based on the same principle. if you vist that page you posted above, take your mouse pointer and highlight everthing (CTRL+A). Now you will notice all the images will be slightly dithered in blue. What the trick was, is they made a table that have some rows and columns. in some of these colums they do not put text, they place images as the background. here, look. http://www.faceparty.com/images/ctr.gif.
You can do the same as well, use a image editior program such as mspaint or I would suggest photoshop and create the corners. once they are saved, create your html page to have a 3 columns. use the end columns for the images you created. and the center column for specifying a background color. remmber, any overflow that exceeds the height of the table will cause the table to grow in size, so you dont need to worry about the height!