omfg... if you want good quality projector, get a DLP projector. i saw spiderman2 on a HP VP6121 ODLP hooked up to a laptop and it was fukin awesome... watched the movie at atleast 120inches across... coulda been bigger but the wall wasn't big enough :P
it actually surprised me.. it is so clear and the pixels are practically invisible. anyway, good luck.
yea but it is pretty expensive... for a desktop, anything, with a decent video card. and for that sharing cable question, there is probalby something out there that lets you share the cables for both devices, but i haven't seen one.