The reason "onclick" is not validating is because it is a Javascript element, and not really part of the web standards. Technically, you should be using Javascript to add the event handler to that node, instead of including it in the HTML. However, this is super-complicated and not really necessary.
If you <i>really</i> are worried about web standards, you wouldn't be using a <FONT> tag in the first place. Putting styling information in HTML is so 1999
. I know you're using Dreamweaver, but
CSS (Cascading Style Sheets) are really the wave of the Internet-future. Give the w3 site a bit of a read; it's pretty interesting.
I wouldn't worry too much about validating. Technically, your code isn't "broken" in any way. It's just not as perfect as it could be.