Calvin,
I like the overall design, and I think the dashed borders aren't THAT bad. Dashed or not, they do break up your page elements, and the menu is outside of the border, so it feels like it's not an important element. Perhaps the menu could be inside the first section or the border could surround all the content and not each piece individually?
As frinkky said, you've got a lot of validation errors. But most of them are easy to fix.
Your DOCTYPE is set to XHTML 1.1 which is a pretty strict standard. You might relax that to XHTML 1.0 Transitional--see the class A List Apart
article for the syntax. That gets rid of five errors right away.
Then make sure that you're following the basic rules that are different between HTML and XHTML:
1. All tags and attributes in lowercase: "title" not "TITLE", "meta name=" not "META NAME="
2. Close all tags, including "empty" ones: <meta ... /> with the final slash
3. Encode all ampersand and less than characters
After those fixes you're down to 15 errors, and they're mostly about the ampersands in the URLs in your links at the bottom and fact that the "embed" tag is not standards compliant. See code.google.com/p/swfobject/ for a workaround.
I agree with Midgard that the backgrounds for the sections need to be stretch for the longer "Graphic Design" header (it looks fine in WinXP IE and Mac Firefox, but is crowded in WinXP Firefox). See the many "rounded corner" tutorials online for how to use several images to outline elements of differing sizes. Then test in several browsers.
Also, consider some way of separating your links at the bottom. Only after hovering over them can I tell where one ends and the next one begins.
Good luck!
Alan