If your PC has gigabit ethernet then there is about 99.9% chance you won't need a crossover cable, if you have an older 100m/bit card you will need to check the specs as its not so common, some brands name it different but it will usually be called either-- Auto uplink and trade, Universal Cable Recognition, Auto cable Sensing or something similar.
damnit, if only i knew about this before plunking 6 dollars down on a crossover cable when i have so many normal ones around
Personally i find it better to just buy the crimping tool and a small bag of heads. They are great to have when wire near the head snaps and you need to replace it. You can also save a butt load if you just buy one of the unheaded spools of cable and put the heads on yourself..