Four years ago I installed some Cat5e cable throughout the house (that’s Ethernet cable for you non-network types). Last time it was for three upstairs rooms, and it went pretty well despite the sweltering heat in the attic.
Last week I finished installing another outlet in the den. This one was harder since the cable ran two stories and across the house, from one side of the attic to the far side of the basement up to the den, but the result is totally worth it. It was free since I used exactly the cable I had left from four years ago with 1′ of extra. The PS3 can now stream NetFlix and media from other computers to the TV, no stuttering or dropouts like I got on the wireless. And I can still crimp cables like nobody’s business.