Ray,

Is lightning a problem in your area?  If so, forget the buried Cat 5/6 idea.  I have learned 2 very expensive lessons from buried Cat 5.  The first time it just got the NIC in a laptop.  The second time it got just about the entire computer network.  We have replaced the buried CAT 5 with fibre optic now and that is not cheap, but far less expensive than replacing the entire computer network.  When you have buried copper, it is not a matter of if lightning will find it, but when lightning will find it.  Wireless data rates are not near as high as wired.  If you are not moving large files, wireless will do the job.  If you need to move large amounts of data look at fibre.