HTML:
<button value="submit" class="submitBtn"><span>Hello. I'm a cool button.</span></button>

CSS:
button {border:0; cursor:pointer; font-weight:bold; padding:0 20px 0 0; text-align:center;width:auto; overflow:visible;}
button span {position:relative; display:block; white-space:nowrap; padding:0 0 0 20px;}
button.submitBtn {background:url(btn_blue_right.gif) right no-repeat; font-size:.8em;}
button.submitBtn span {height:30px; line-height:30px;background:url(btn_blue_left.gif) left no-repeat;color:#fff;}
button.submitBtn:hover {background:url(btn_blue_right_hover.gif) right no-repeat;}
button.submitBtn:hover span {background:url(btn_blue_left_hover.gif) left no-repeat;}