Here's how to make a crossover cable with 10BT, or UTP cable. They look like large telephone cables.
Data is sent from and received into your computer through the network card (or 'NIC') through the network cable. It's important to note, however, that not all of the strands of cable are actually used. In fact, most 10BT cables have 8 strands of wire, and only 4 of those are used-- 2 for sending, and 2 for receiving.
Looking at the RJ-45 (phone cables use RJ-11) connector, with the flat side toward you, you can clearly see the wires going from the cable into the connector. Counting from the left, wires 1,2,3 and 6 are the 4 wires that actually send/receive. Wires 1 and 3 form one pair, and 2 and 6 the other. Ordinarily, these pairs go straight through the cable, and connect at the other connector in the same order. We're gonna mess with the cable's world. :-)
Wire one end of the cable as usual, with wires 1,2,3, and 6 in their normal places. At the other end though, just reverse the pairs! That's right, on the crossover end, you'll have: 3,6,1,2. Here's a little text picture of each end:
Regular end:
|1|2|3|4|5|6|7|8|
^ ^ ^ ^
And at the crossover end:
|3|6|1|4|5|2|7|8|
^ ^ ^ ^
^ marks a wire that we're actually concerned with. The others are either not there, not necessary, or left in for consistency. I personally find it nearly impossible to get all 8 wires to line up when jamming them into the connector.