I found this good tutorial on How to convert a .psd to a Drupal Theme. The author is Vancouver's Alexa Booth. An experienced Drupal themer, Alexa takes one through the basics of theming. So far I have worked through Part I and II and I learned a lot. Hope you will too. Note: This tutorial uses Drupal 5.x.

• PSD to Drupal Theme Tutorial Part I

• PSD to Drupal Theme Tutorial Part II