After I've done my mockup, I use ImageReady and proceed to create slices of the template that need to be cutup into images to fit into a table, ImageReady will do this for you and upon save for webpage create your images and your html file.
Here's some tips and tutorials that may be useful in PS:
Create a Web-page header with a tabbed navigation bar:
Phong has some good tutorials:
Some other good-tutorials: