I use Adobe Illustrator to mockup my web site designs. I prefer to use Illustrator because Illustrator is designed to create layouts, whereas Photoshop is not designed to create layouts (in my opinion).
I found an excellent post on how to create a web mockup with Illustrator; however, I created a bunch of these mockups for you and saved them as Adobe Illustrator files. The following are some example screenshots:
You will find the Illustrator wireframes in the attached zip file. You should be able to download these files, unzip them, then open them up in Adobe Illustrator. The mockup objects are locked in the first layer. To edit them, you will want to unlock the layer.
I have added slices to all the wireframe areas and you only need to divide them up further to match your design or export for web and devices as they are sized now. You will find the slices in the bottom template layer, and you only need to unlock the slices layers to edit slice sizes and placement with the slice selection tool.
You can also download a PDF file of all the wireframes. They do not have slices, but you can print and draw out your design. Forget napkin drawings forever!