Category-5 cable is what you use to wire an Ethernet network. Also known as 10BaseT/100BaseTX cable. Think of it as telephone wire on steroids. Sure, it's got the same twisted-pair concept behind it, but the material is of far greater quality, and more pairs are used for a connection (4 pairs for Ethernet, as opposed to one pair for one telephone line.)

AFAIK, there's two different methodologies here-

568A wiring layout

      |white-green  |-
      |green        |-
cable |white-orange |-  
------|blue         |- contacts  
------|white-blue   |-  
      |orange       |-
      |white-brown  |-  
      |brown        |-

568B wiring layout

      |white-orange |-
      |orange       |-
cable |white-green  |-  
------|blue         |- contacts  
------|white-blue   |-  
      |green        |-
      |white-brown  |-  
      |brown        |-

Both 568A and 568B are wired the same way on both ends. And of course, because we'll all need it someday:

Crossover (for connecting two machines without using an ethernet hub)

wiring layout- one end

      |white-orange |-
      |orange       |-
cable |white-green  |-  
------|blue         |- contacts  
------|white-blue   |-  
      |green        |-
      |white-brown  |-  
      |brown        |-

other end

      |white-green  |-
      |green        |-
cable |white-orange |-  
------|blue         |- contacts  
------|white-blue   |-  
      |orange       |-
      |white-brown  |-  
      |brown        |-