You have the iPod Nano second generation silver. It has a dock connector, which is a good thing, and holds about 500 songs - small for an iPod but about ten times larger than the CD changer it will be replacing. If you are selective in choosing the right adapter, in the future you can upgrade to a larger iPod and still have compatibility. The correct adapter will give you head unit control and iPod charging capability.
I recommend that you order the Grom iPod adapter. Get the latest version that is 3G compatible and backwards compatible with most (not all) older iPods. On their website, Grom specifically states that this adapter it is compatible with the Ipod Nano second generation. Be sure to get either the 8-pin cable or the combination cable, as the MBUS cable (the one with the square connector) is the wrong cable for the NSX.