Bjarne D Mathiesen wrote that SEEdit would not generate good code. I think that is not true. I spotted only one "incorrect" MIME type: in the XHTML 1.0 Basic Template of SEEdit, and one "half incorrect" MIME type in the XHTML 1.0 Frameset Template. See http://www.w3.org/TR/2002/NOTE-xhtml-media-types-20020801/xhtml-media-types.html (especially the 3.5 Summary there) for better information on MIME types for XHTML,
SEEdit has an excellent support for validating XHTML via Tidy, which is included somehow in the program. But to be 100 % sure, anyone will have to rely on his/her own knowledge and understanding of the subject. Nobody's perfect.
I highly recommend SEEdit as a tool for making better websites, because it's so damn efficient, used either alone or together with other authoring software.
Heinz J. Malcharzyk