Apart from a sketch book, pencil and my Meta Stationery ruler, my projects commence with Adobe Photoshop. Although I’ve been using Photoshop since 2006, I truly believe I use less than 5% of the functionality.
That’s not to say I don’t know it very well. In order to create website, you don’t really need to use that much, you just need to use it well. Every website I create passes through Photoshop at some point. The development process continues with a finished design, before slicing up the elements to integrate within the CSS of the planned website.
The tools within Photoshop are ample for web design but as we progress into CSS3, you will rely less on your design tools and more on your coding techniques to create the effects that set each project apart.