For what it's worth, here's a few things I learned while fooling around with Cat5 wiring.
First off, I miswired a bunch of cables by assuming that all that mattered was matching each end up: pin 1 to pin 1, etc. Each twisted pair was next to the other. Interestingly, only the miswired cables that were shorter than about 10 feet worked. The problem is that, for some reason, consecutive pairs of pins are not used as transmision pairs. I'm not really sure what forces are at work here (cross talk?), but it really does matter how you wire them.
I don't typically like "reading directions" and would much rather just try to figure things out for myself, but when it comes to Cat5 wiring, read the directions.
The other thing I learned (the hard way) is that it's important to get a good crimp. This crimp tool didn't always work:
Belkin Crimp tool
I think because it did a poor job of pushing the pins down into the wire.
This crimp tool always worked:
Cables To Go Crimp tool
and did a great job of pushing the pins down into the wire. There may be other good crimp tools out there, but these are the two I have.
Lastly, don't bend the Cat5 cable at a sharp 90 degree angle. It's temping to do this while trying to run the cabling around walls, etc., but there's a good chance that this will cause mysterious problems in your network.
Hope this helps,