How do modify the look and feel of a Sharepoint site?

I somehow got lumbered with deploying SharePoint at work. I hate it, even the simplest things seem to be unnecessarily difficult.

I've seen a few resources scattered around, but they all seem to stop short of helping me really take control of the css.

Can someone point me in the right direction?

EDIT

• I'm not afraid of the css itself, I just cannot seem to find the right place to edit it.
• I do have SharePoint Designer 2007

From stackoverflow

• SharePoint calls this general feature "Branding" -- if you search for SharePoint Branding, you will find a lot of resources. This one looks good:

  http://www.heathersolomon.com/blog/articles/brandsppart1.aspx

  DrG : ah ha, thanks for the tip!