I'm not exactly sure because I don't have IE6 on this machine, but you forgot to mention that there is also this in your stylesheet:
Code CSS:
h1.logo, h2.description, h2.contact-info {
display: block;
float: left;
padding: 0;
text-indent: -9999px;
}
And because your h2.contactinfo has a margin-left you may be a victim of the IE6 double margin bug. What happens if you give the h2.contactinfo a display:inline declaration?
Off Topic:
I don't know if it's a good idea to make a sprite like that.
Edit: whoa, there actually is an OT tag 
Edit #2: beaten by the master...
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