It's important to understand that, even if you're running BooBooHTTPD on the Hamilton '95 operating system on a Blaze-24 graphics card, a security flaw is still a security flaw. If there's a buffer overflow out there, you can be attacked. Being obscure just reduces the chances that someone will go after you. If you become someone's pet project, they can go after you, and quite possible r00t your machines.
However, obscurity can give you time to get patches and updates applied before the exploits can be tailored to your particular system. It helps stave off panic, but you still have to keep current on security patches.