Here is an alternative to rubber headers as mentioned on web-graphics. You don't need the large image to create the left curve and the width is infinite. Plus if the images don't load you still have the background color to pull out the white text.
See the code below to see how it was done.
images used
A Header Text at 250px
A Header Text at 90%
Click here to see in a fluid format.
h4.rubberhdr {
height: 20px;
margin: 0;
padding: 0 10px 0 0;
background: url("/images/temp/right.gif") top right no-repeat;
font: bold 12px sans-serif;
}
h4.rubberhdr span {
display:block;
height:18px;
padding: 2px 0 0;
margin: 0;
background: #A407FF url("/images/temp/left.gif") top left no-repeat;
color:white;
text-align:center;
white-space: nowrap;
}