SharePoint internet version licencing

You cannot have both Internet version and Standard/enterprise version of MOSS 2007 on the same farm. There is no limitation from the product side, but more from the licencing policy. If you wish to have both Internet and Intranet access in the same Farm, then you need to buy two licences(Internet and Standard/enterprise) of MOSS 2007 for your Index server. Also, remember that you need to buy Windows Internet connector licence for each of the Windows 2003 server exposed to internet(which will host annonymous content).