Sorry if I wasn't clear above, but my intent is to default to using the <p> tag.  There are dozens of reasons to use <p> tags to mark-up paragraphs as opposed to using <br> or <div>, many related to accessibility and syntactical HTML, but now is not the time for that discussion... 

I have found with further testing that the solution Adam provided above does cause the editor to use <p> as the default formatting when pressing the Enter key in IE 6, but not Firefox (I haven't tested in IE 5/5.5 yet).  I've also been having a problem with Firefox frequently crashing at the point where it starts to load the editor.  Telling my users to simply use IE as opposed to Firefox is not an option.  It seems this product is not as compatible with Firefox as it advertises.

Adam, if you or anyone can provide some insight it would be much appreciated.