L.E.D.s how to?

OK, you know their voltage. You need to know what current they run at. Commonly LED's can run from between 16 and 24 milliamps. You'll need to know the voltage you've got available to run them. Most computers should have a 5v supply available somewhere in the box. Then it's just a matter of using ohms law. Current (I) = Voltage (E)/ Resistance (R). Rearrange to determine R. R=E/I. Assuming a 5 volt supply and run at 20mA. R=5/20E-3=250 ohms. I don't know if a 250 ohm resistor is available, but 270 ohms definitely is. Connecting at 270 ohm resistor in series with the LED and connected to a 5v supply would run it at about 18mA. It might actually be a little less considering the voltage dropped across the LED. (should be about 0.6 v, which would run it at 16mA)
Of course, this is just an example. Just remember R=E/I and some simple transposition if needed.

I can give you a link to an xbox forum that may be able to help as well. I'm not going to post it here (it'd probably just be deleted in any case). If my explanation doesn't help, PM me your email address and I'll send you the link.

I've had a proper look here's the specs;

REVERSE VOLTAGE:5.0 V
DC FORWARD VOLTAGE:3.3V TYPICAL/3.5V MAX
DC FORWARD CURRENT:20mA