Collisions and cross talk are two different things. Collisions are when two devices on a N/W try to transmit at the same time as far as I'm aware. Technically it might not be this simple though. Crosstalk is when data signals travelling down one cable "transmit" due to their high frequency, and cause a 1 to switch to a 0 or vice versa on an adjacent cable. That's why your high speed IDE cables have twice as many wires - there's a ground wire in-between every data cable to stop the cross talk. It's also similar to why cat5 and other data cable is twisted. The pairs of cables carrying data are twisted together so that any interference encounted along the way gets transmitted to both wires equally and can be cancelled out at the other end, so eliminating the need for expensive sheilding for the most part.
You also want to make sure that you aren't running the cable parallel with any power cables/wires. Doing so for more than a few linear feet can cause some interesting errors.
Also, make sure that the cable isn't kinked or coiled up with itself. Cat5/Cat5e cables carrying signal are much more likely to cause crosstalk with themselves than each other (in typical network installs I put 300+ cables running for 50+ feet in the same conduit). However, if you're like many people and you buy the Cat5 from best buy, it comes coiled up fairly tightly. When many people unwrap them, they don't always unwind them, just plugging the two ends into computers a few feet apart. This causes havoc as you then have anywhere between 10 and 50 feet of cable coiled up together.
If you want to eliminate collisions, you will need to purchase a switch (not a hub) and make sure it and your network cards are capable of "full duplex" operation (i.e. capable of talking and listening at the same time). There is no such thing as a collision on a full-duplex circuit.