Anthony, if you ever need some help/tips for WHMCS templates, let me know.

Your best bet for the WHMCS template though, is to go back into header.tpl, and just hard code the class in it for the highlight. The problem with WHMCS is that the URL schema's will end up breaking any kind of Smarty code you setup to highlight the nav as you go. But since you're ust highlighting "Support" really no need for anything else, so easy fix for ya.

ETA: Also, http://www.vimdata.com/clients/serverstatus.php. You should open up serverstatus.tpl and remove the PHP Info link. I'd advise against having that available publicly. But should you do choose to keep it, you'll need to fix the URL. You forgot the http:// so it's linking it wrong