I managed to obtain this kind of table layout:
fixed - dynamic(50%) - dynamic(50%) - fixed
http://jsfiddle.net/ihtus/ksucU/

But how do I get this kind? fixed - dynamic(30%) - dynamic(70%) - fixed

Here's my CSS:
table {
width:100%;
border-collapse:collapse;
table-layout:fixed;
}
td {
border: 1px solid #333;
}