If you want to stick to graphics =) and get rid of the text link in header and make the whole image be clickable, then you might try adding this to your CSS.. it works in the way I included it in mine anyway =)
#header a {
display:block;
height:100%;
text-indent:-500em;
text-decoration:none;
}
That should make your whole header image a clickable link and remove the blog name and tagline text. If for some reason it's not centering for you like it was borked for me in Firefox till I figured it out.. Now I've never used your theme, but you might try adding this to your css.. it worked for me in mine. Here's example from yours:
.header {
border-color:#AAAAAA;
background-color:#F8F7EF;
margin: 0 auto; <--ADD THIS BOLD LINE
height:124px;
background-image:url("images/header-bg.jpg");
background-repeat:repeat-x;
background-position:center;
border-style:solid;
margin-bottom:5px;
border-width: 1px;
padding-left:10px;
}
Not sure if it's gonna be helpful, but I hope so.