inhouse WLAN

I’m new to this technology and am anxiously gathering as much info as I can. I would like to network a number of PC’s in our shop (surrounded by steel beams and concrete) and network them with our in-house network. My general plan is to run cat-5 from pc to hub, hang this in the rafters somewhere, then wireless to our server. The distance from the proposed area for the hub and the server is about 50 meters. Any thoughts on equipment I will need for this project and other thoughts such as interference through the fire-wall (concrete and steel) with the radiowaves, or anything else you can think of that I should consider will be welcome.