First, don't be misled by the term "netbook". A netbook is just a small, low-priced, low-power laptop with relatively small solid-state drives. Because the display and drive capacity are small, netbooks are basically just good for email and surfing. If you're going to do coding or even much word processing you'll need something more like a traditional laptop or desktop.
Up until about 1999 the laptop market was completely crazy. The technology was in a state of violent flux, with "standards" phasing in and out and prices dropping like rocks. Things are beginning to settle out a bit more now.
One sign of this change is that there are now a couple of laptop lines that are clear best-of-breeds for reasons having as much to do with good industrial design and ergonomics as the technical details of the processor and display.
In lightweight machines, I was a big fan of the Sony VAIO line. I owned one from early 1999 until it physically disintegrated under the rigors of travel in late 2000, and could hardly imagine switching. They weigh 3.5 pounds, give you an honest 3 hours of life per detachable battery pack, have a very nice 1024x768 display, and are just plain pretty. Their only serious drawback is that they're not rugged, and often fall apart after a year or so of use.
If you want a full-power laptop that can compete with or replace your desktop machine, the Lenovo (formerly IBM) ThinkPad line is the bomb. Capable, rugged, and nicely designed. I now use a ThinkPad X61, the lightest and smallest machine in the line, and like it a lot.
These machines are not cheap, though. If you're trying to save money by buying a no-name laptop, here are things to look for:
First: despite what you may believe, the most important aspect of any laptop is not the CPU, or the disk, or the memory, or the screen, or the battery capacity. It's the keyboard feel, since unlike in a PC, you cannot throw the keyboard away and replace it with another one unless you replace the whole computer. Never buy any laptop that you have not typed on for a couple hours. Trying a keyboard for a few minutes is not enough. Keyboards have very subtle properties that can still affect whether they mess up your wrists.
A standard desktop keyboard has keycaps 19mm across with 7.55mm between them. If you plot frequency of typing errors against keycap size, it turns out there's a sharp knee in the curve at 17.8 millimeters. Beware of "kneetop" and "palmtop" machines, which squeeze the keycaps a lot tighter and typically don't have enough oomph for Unix anyway; you're best off with the "notebook" class machines that have full-sized keys.
Second: with present flatscreens, 1920x1200 color is the best you're going to do (and that is on a 17in widescreen, which translates to a large notebook. On normal size notebooks, a maximum of 1440x900 is more common). On travel machines like the Lenovo X serties, you're still stuck with 1024x768. If you want more than that (for X, for example) you have to either fall back to a desktop or make sure there's an external-monitor port on the laptop (and many laptops won't support higher resolution than the flatscreen's).
Third: about those vendor-supplied time-between-recharge figures; don't believe them. They collect those from a totally quiescent machine, sometimes with the screen or hard disk turned off. Under Windows, you'd be lucky to get half the endurance they quote; under Unix, which hits the disk more often, it may be less yet. Figures from magazine reviews are more reliable.
Fourth: You can now avoid many of the driver hassles involved in getting some devices on your notebook to work (or week well) under Linux by purchasing a notebook with Linux pre-installed. Dell has recently started to make noise in this regard in the Linux community. Taking this approach limits the set of notebooks you can consider, but the one you get is likely to "just work" (including sound, useful capabilities like suspend/resume, and even hotplugging of external displays and projectors) to a much higher degree under Linux than others.