Cat3 SHOULD work for MOST applications. Cat5 & Cat5e is what is currently available. If this a new install, I would go with 5e or install EMT/NMT for an easier upgrade path. If this is an existing installation, AND the wiring is in good shape AND the customer is only doing basic Ethernet use, Cat 3 will function.
I'm not sure how much future proofing you should be doing, because the future might be Wireless and all of the installed cable will be not used. If you are going to install network cabling, I would think that a power receptacle should be in the next stud bay over.
Larry C
