If you want to go directly from the PC to the Xbox, your cable should be crossed.
If you want to go from Xbox -> Hub -> PC, your cable shouldn't be crossed.
Quick tip on how to see if the cable is crossed:
To tell if your network cable is crossed you have to look at the RJ45 on each end of the cable.
If the wires inside the RJ45 is different than on the other RJ45 it's crossed.
If the wires look the same on both, it's not crossed.