Not Sure With Your Nintendo DS System?

1. Check the serial number, it usually on the bottom of your DS, next to the bar code, then check two letters do begin with :
        Nintendo 3DS: serial numbers starting with "CW"
        Nintendo DSi XL: serial numbers starting with "WW"
        Nintendo DSi: serial numbers starting with "TW"
        Nintendo DS Lite: the serial number starts with "UG"
        Nintendo DS original: the serial number starts with "NU"

2.  Where is the power button located on your system?
        Nintendo 3DS: located at the bottom right-Touch Screen (lower screen).
        Nintendo DSi XL: located at the bottom-left of the Touch Screen (lower screen).
        Nintendo DSi: located at the bottom-left of the Touch Screen (lower screen).
        Nintendo DS Lite: located on the right side of the system.
        Nintendo DS original: located near the top-left of the Touch Screen, on the D-pad.

3. What is the location of the power indicator?
        Nintendo 3DS: withink the power button.
        Nintendo DSi XL: located on the left hinge.
        Nintendo DSi: located on the left hinge.
        Nintendo DS Lite: located on the right hinge.
        Nintendo DS original: located on the bottom-right of the Touch Screen.

Source: http://www.nintendo.com/consumer/systems/selectds.jsp