I'd say put in conduit - and go bigger than 3/4" if you can. Then you can go back once it's built and pull Cat5 yourself. Then, if you ever need another Cat5, you can add it. If you ever want to put in Coax, Fiber, or other low-voltage cable, you can. The cable is cheap when you buy 1,000 ft spools - I think I purchased 1,000 ft. of riser-grade Cat5 from Lowes several years ago for $50 - still have at least 250 feet of it too.