I work for a large local government organisation who are about to embark on using SharePoint to replace our ageing intranet with an all-singing all-dancing collaborative sit
Without knowing your complete requirements, Windows SharePoint Services 3.0 (as opposed to Microsoft Office SharePoint Server 2007) is a good solution. Licensing is free and it works well as the framework for public-facing websites. Using WSS 3.0, you'll be able to take advantage of your MOSS 2007 infrastructure, administration, and user training. I have developed a number of successful public-facing sites using SharePoint for various customers and am happy with the results.
This link provides a comprehensive comparison between WSS 3.0 and MOSS 2007:
http://office.microsoft.com/en-us/sharepointtechnology/FX101758691033.aspx