It doesn't take a huge outlay to be able to develop websites these days. What it does take to develop good websites is an in-depth experience, not just of the technology, but of your customers and the process of marketing them online.
That said, we present the first in our series about the tools a web developer needs to get started, starting with graphics tools.
The main thing you need if you're building any kind of sophistication into your design (whether you're designing the site or receiving/setting up the artwork in order to build the site) is a graphics editor which handles layers.
Photoshop is the industry standard package with all the bells and whistles, and comes with a hefty price tag to match. You can do amazing things with photographs, although you'll need to learn about the tool in order to create nice buttons and graphics. Thankfully, there are now lots of youtube videos which help with that. Or you can read a book...
Photoshop Elements is a cut-down and very reasonably priced version of Photoshop. The only thing I've needed that it lacks is grouping layers, which can be important if you're receving artwork from a designer who uses Photoshop 'proper'.
Fireworks is another Adobe offering, really aimed at the graphics side of the web rather than photo editing, so while it won't help you with that nice header banner you would like to create, with the face merging into a landscape, it'll do buttons nicely. It doesn't have a huge market so you may find that designers you'll deal with normally use Photoshop.
GIMP is a free tool which offers something near the sophistication of Photoshop, with some nice extras besides, like a series of effects and animations. The down side is the clunky multi-window interface, but you can certainly get used to it.
Paint.Net is the baby of the group, another free tool, with various features missing such as retaining text information inside a layer. That said, it's often good for your customers who just want to crop and resize pictures before putting them online and don't want to pay for anything more sophisticated.