This is a link to a proper weatherproof projection enclosure...http://www.displaydevices.com/products/staging_solutions/epe.html
here as well...http://www.tempestlighting.com/products.html
You are looking for a digital signage PC, which there are many (hundreds) to choose from.
You really should be going to a professional installation company for this work as it appears you know nothing of projection at all, you just are looking for a solution. For a professional solution when you don't know anything about the subject, I would turn to experts and pay them appropriately for their engineering time. Any commercial A/V dealer should be able to help you out.
I struggle with this as there are answers to your question on outdoor enclosures just a few posts down, so if you aren't willing to do this basic research, then you truly do need someone to help you get this done properly.
- Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.