<img /> tags need alternative content with "alt" attribute. "dots.png" is not a content. Using CSS backgrounds instead.

"border" attribute is not a valid attribute for <img /> tags. Using proper CSS instructions instead.

<br /> is not a valid strict xhtml1.0 tag. Not semantic. Replacing it by CSS instructions on semantic tags.

Adding semantic h1 tag to surround the logo. This could be better for text or braille navigators and crawlers as well.

center is not a valid strict xhtml1.0 tag (not semantic). At least, replacing it by a div with "center" class.