I am a fairly new D40x owner, having upgraded from a Canon A620 point and shoot (PS).
There are basically 2 differences between the D40 and the D40x
- the 6MP ISO 200 sensor vs the 10MP ISO 100 sensor
- the slightly faster burst rate on the D40x (3fps vs 2.5 fps)
Everything else about the two is the same. The same features. The same electronic-only focus control for the lenses.
Ken Rockwell has a good in-depth review of the D40, the (in his opinion) overpriced D40x cousin, and a full feature guide to both. Start here:
http://www.kenrockwell.com/nikon/d40.htm
http://www.dpreview.com/ is also good for reviews, as mentioned above.
From my own experience, I have two AFS lenses: the 18-55 kit lens and the 55-200 VR. That covers most of what I want to do, they work just fine with the D40/x, and they're both inexpensive. I also have the 50mm f/1.8D. As mentioned, yes, it is manual focus on the D40/x. No big deal, just manual focus it. It's easy to use, takes nice pictures, and has a nice shallow DOF for macro shots. Basically, if I'm taking the time to compose a careful macro shot, then MF is no extra time, and better control than the AF gives anyway.
I briefly borrowed a Canon XTi as well, which is Nikon's primary competitor to the D40x. It works well too. There's an older version of the XT series with a lower-res sensor that is probably a good alternative to the D40 if you want to save a few bucks.
My main benefits from the SLR vs the old PS:
- bigger sensor = better low light sensitivity. The D40x takes acceptable pictures clear up to ISO 1600
- bigger lens opening = truly wider apertures = shallower DOF on macros
- multiple lens choices, and they take standard filters without weird extension tubes
- RAW mode for more control over the sensor-to-jpeg conversion (yes, I like to photoshop my pics)
- vibration resistant lenses available (my A620 does not have stabilization)
- slightly better resolution (10mp vs 7mp) gives a few more pixels for crops
Main losses from the PS:
- size, I can pocket the A620
- price, I've spent around 4x as much on my Nikon kit
- batteries, A620 uses standard AA, Nikon uses its own battery
Hope this helps,
Charles