Jag, if you're trying to "future-proof your wire run, you should definitely run an HDMI cable. It is the coming standard for video and audio. Already, displays and sources are hitting the market with HDMI ins and outs.
And, as Ken mentioned, you can make longer cable runs (a common thing with projectors) without running into the problems that some have experienced with long DVI runs. HDMI is backward compatible with DVI (using an adapter, or HDMI/DVI cable). But, if possible, avoid a source with HDMI out connected to a projector (or HDTV) with only DVI in. Some (but not all) have experienced a problem with that combination. In the near future, I'm going to have just this setup (HDMI out DVD player to a DVI in HDTV. I'll try to remember to post if I have any problems). A source with DVI out to a projector with HDMI in has worked fine and, of course, HDMI to HDMI works fine.
If you REALLY want to be safe, run both a component AND and HDMI cable. You'll REALLY have your bases covered.
And yes, the HDMI (or DVI) cable will probably be more expensive than the component cable, but the picture will be commensurately improved.
