I'm not entirely sure what you're asking, so help me if I'm giving you irrelevant information.
At my church we are using a Lenovo Thinkcentre desktop with a Core 2 Duo, 4gb ram, a Geforce gt 220, dual monitors. It hooks into an Ocean Matrix video switcher/scaler unit, which feeds a single VGA up to the main projector. The switcher can accept DVI, VGA, Component, RCA, etc. and scale it to the correct resolution of the projector. To duplicate the signal to the rear projector, it uses a VGA splitter on the output of the Ocean Matrix box, with one output going to the front and one to the back.
So, if you wanted to get multiple video feeds into the projector, a switcher/scaler unit is what you'd need, and a VGA splitter to give both the projector and the DVD burners signal. You may find a DVD recorder that accepts VGA input, but most don't so you'll need an appropriate adapter to convert the signal. Then to use other connections, all you'd need to do is plug your device into the back of the switcher/scaler, select that input, and there you go.