Is there a difference in using DVI or component cables for a 720p or 720i projector? I don't want to spend the extra $50 for a DVI cable if I can just use the component cable.

A DVI cable will look something like a VGA cable that is on your computer monitor. It provides higher quality than component, but like you said is more expensive. Also, older HDTV's (4+ years?) don't have DVI inputs. Since you are using a projector, it will probably be worth it.

I read somewhere that the DVI cables only make a difference if you're at 1080 and up. Is this true?

Well 1080 is the highest resolution so it cant go any higher than that...but I never heard anything like that. i suppose it could be true.....

Who told you that 1080 was the highest resolution? Many of the best 9" CRT projectors (Accurate Inaging 9, Reference 9X, Sony G 90, Runco, Ampro 4300) will do 2500 X 2000 and more (5,000,000 pixels), resolving over 2000 horizontal lines. This is double the resolution of HDTV at 1080P.

DVI or HDMI is by far the best connection for digital signals. It is important to buy the best cable that you can afford and stay within the cables maximum length capibilities of approximately 66 feet. For longer runs, you can buy a small in-line signal amp.

Good quality DVI/HDMI cables run from $150.00 or so and up. Look at Monster Cable, Audioquest, Straightwire, XLO, Wireworld and Kimber Cable

Well since this is under the Digital TV forum, I figured he was using this projector for as a TV, and not for a computer. Thats why I said 1080i is the highest resolution, because TV comopanies dont broadcast at anything higher than that.
@Bigbob, change your signature picture, its WAY to big, also edit your post to exclude your sig, its making this webpage too wide.

I ended up getting the monster component cables with my HD cable converter box and it's beautiful watching football on 100" HD

OOo pmaknelho, I'm drooling just thinking about that right now..:P

Good point. 1080P is the current maximun resolution for digital broadcast TV or about 2,100,000 pixels. My Sony G90 is capable of 2500 x 2000 or 5,000,000 pixels

My bad on the signature. It has been corrected. Bob