You should use a separate css for the print media. This allows you to hide/show portions of the page when it gets printed.
html :
<div class="dont-print-that">
blah
</div>
print this!
include:
<link rel="stylesheet" type="text/css" media="print" href="print.css" />
print.css
.dont-print-that{display:none;}
The other solution is to open a new window with only the content you want to print. You could either do that in a popup or an iframe. Personally I find the CSS solution more elegant, but that's up to you.