This is a compilation of tips, tricks and recommended settings for the Nikon D40X, and is based on various discussions in forums and other D40X sites.
Want to know whether your old Nikon / Nikkor lens is compatible with the D40X? — This post by LilKnytt has a link that points to a Nikon Lens Serial Numbers site where you can determine the year of manufacture and type of your lens by serial number, and other lens construction details and features. Basically, if your lens is an AI Nikkor lens or a lens type manufactured after the AI series, you can use it on your D40X (but check your manual first). AI Nikkor lenses (see this Nikon Camera and Lens Compatibility Chart for details) were manufactured in 1977 to mid 80’s. Traditionally, it’s reasonably safe to assume that any lens manufactured by Nikon on (as long as it’s an AI lens — designated as Type Ai lens at the Nikon Lens Serial Numbers site) or after 1977 is compatible with Nikon Digital SLR cameras in general, but if you look carefully at the Compatibility Chart, you’ll notice that pre-AI lenses CAN be mounted on the D40 / D40x, that’s a nice advantage in the D40X’s favor.