I agree with this. It's so cheap (especially compared to the rest of the cost of building a house) that you'd be mad to cut corners.
Someone above mentioned CAT 6. This is a decent standard - CAT 7 has thicker wire, I think, so you may have more trouble with bends and termination.
Also, make sure you have solid copper wires, rather than cheaper copper coated aluminium (sometimes abbreviated CCA). I don't know whether CAT6 even comes in CCA form, but worth checking.
Another tip: if you have a central place for things like AV equipment, consider running a spare empty duct or two with draw cord to each TV position. That way, you'll easily be able to replace or upgrade cables, or run new cables in the event we end up with a new standard in 10 years. Again, cheap and easy to do now, versus a nightmare in the future.