My suggestion is to wait until you have your projector. DVI vs component will really depend on your projector. I have a plasma, and most HD looks better w/ DVI but I don't have all the adjustments as I do w/ component. And standard def DirecTV looks better in composite. So really the fool proof way is to run EVERY type of cable to cover your bases. BUT that gets $$.
As you've probably found out, long DVI cables aren't that cheap. (I don't know how long your run is.) Long component cables are cheaper. But you won't know which is better until you watch it. If you want to build LONG component cables (>50'), you want to use RG6 coax and then terminate the ends w/ RCA or BNC's and then use BNC to RCA. That way the cables will be shielded. HOWEVER, these will be THICK.
That being said, you can try blue jeans or pacific cables.
Pacific 
