Ah... well, I actually use component, composite, and S-video for everything and I use a video distribution amplifier (
www.extron.com) to send video to both display devices at the same time. It doesn't hurt the plasma or projector to have video sent to it when it isn't on, so there is always video at both locations.
Then when I want to watch the plasma, I have the plasma on, and when I want to switch (I use Crestron remember), I just press a button on my remote and it turns the plasma off and the projector on. I don't have a motorized screen, but a $200.00 pull down 16:9 screen. It works well and will be better when I can afford to switch my cheap pull down screen with a nice tab-tensioned motorized screen... sometime after I'm in my new home.
Anyway, there are tons of projectors out there falling into many different price categories. The new Panasonic AE700 and the new Sanyo Z3 are both very good values for your money. Check
www.projectorcentral.com for top notch projector information, it is (IMHO) as good as this site is but focused specifically on projectors and nothing else.