More and more of the new LCD and plasma sets have a VGA input on them. This would be the best way. You can purchase long VGA or extension VGA cables.

Some laptops have a S-Video output on them. I have used premade S-Video cables up to 50ft and have had no trouble with them.

If it's for a permanent install, use Cat5 for VGA or S-Video with audio (using baluns) or 2 RG6 coax cables for S-Video (using adapters).