Most browsers (all?) will probably handle these errors and display everything "correctly", they usually accept deprecated elements, attributes and other things that are not part of the specification in case of HTML 4.01.

For example usage of FONT element is not valid, attributes like BORDER are not used (use css instead) etc. I dont know dreamweaver and how it performs validation but that validation within FF or W3C web validator give you comments and explanations so you get an idea how to correct errors. It's really often just use of deprecated elements or something like that.