Back during the September CTP, I would have recommended Expression Graphic Designer over Illustrator.  It was a great vector editor, plus it had some powerful pixel-editing features that couldn't be found anywhere else.

However, the powerful pixel-editing features have been removed.  Expression Design is a crippled remnant of what it once was--  it's now geared only towards generating graphics for WPF projects.  The current version is definitely one to skip.

I liked Expression Web as HTML editors go, but I haven't used Dreamweaver (so I can't make a comparison), and still prefer using a text editor for HTML.