On a previous installation under Windows XP, I encounetered a "HTTP 500 Internal Server Error" and was told to enable the PHP curl extension. It solved the problem then.
I installed Windows 7 Ultimate today and then again installed WampServer. I once again get a "HTTP 500 Internal Server Error" when visiting the front end of Joomla - this time the PHP curl extension is enabled. The admind section is accessible and works perfectly.