External style sheets are better as it keeps the amount of code on the page down which also keeps the page size down also.
Thanks for an answer. I have not worked with css other than changing a few colors in templates when posting. My fear was that I would not be able to convert a template that had css in it to an external. It was easier than I though took about 2 minutes and boy did it reduce the code and page size in the displayed page! CSS is Cool
CSS is very cool and very powerful. Take a look at http://www.csszengarden.com/ for sites that are designed with CSS - check out the different designs on the right hand navbar.
I second the use of an external CSS file. It makes life so much easier if you have to change something site-wide. It comes down to modifying one external CSS file VS thousands of pages by hand or with some script.