No, component video can carry HD. I'm watching it right now. Composite video is limited to 480i, as is s-video.

At present, you have no HD sources. You could connect both the Sony and DirecTV boxes to the 990 (I'd use component from the Sony and s-video from DirecTV), then connect the 990's component output to the projector. DVD is not an HD format, and while some players will output HD resolutions it is still a scaled up image from a 480-line source (and in most cases that upscaling is limited to the DVI or HDMI output rather than component).

Before you run a DVI cable to the projector, make sure that it supports HDCP. If it does not, you will not be able to use HDMI sources with it because they won't be able to establish an HDCP handshake with it and will thus not output video. If that is the case, you can still use component out of an HD satellite box - just don't want to see you run a DVI cable to the projector that you can't use.