The banner has been compressed so much that there is artifacting. You can re-build the pig in Photoshop, Illustrator, or, for free, GIMP?? so that it looks better.
The low-quality image detracts from the site's credibility. For a financial site, it's a good idea to ensure that the site is credible, especially one affiliated with the US gov't. Graphics don't just spruce up a site: they convey a lot about the information contained within it and viewers use this information to decide how believable the site is.
From a study on site credibility: "Nearly half of all consumers (or 46.1%) in the study assessed the credibility of sites based in part on the appeal of the overall visual design of a site, including layout, typography, font size and color schemes." (http://www.consumerwebwatch.org/dynamic/web-credibility-reports-evaluate-abstract.cfm -- a study out of Stanford Univ.)
Because you're affiliated with the Treasury, it'd be a good idea to link to their website in the home page text and, ideally, directly to the page re: Ofc of Financial Edu.
Consider changing the left navbar color or typeface color to improve contrast between the two. Same with the bottom navbar. Same with page title headings -- especially here, actually: tan type on white background is very hard to see.
Put the mission first, not last, on the home page.
Consider shortening the home page. Users shouldn't have to scroll much here (and they won't). You can fix this partially by making your banner shorter.
Use whitespace between paragraphs, and don't use indents (some pages have this, some don't).
Consider constraining the page width. There's such a thing as too much space: not only does it not look especially good, but it makes online reading a bit harder due to line length. Look at some of the most popular websites and you'll see that most don't do this, even media sites that have tons and tons of content (CNN, NYT, etc.). There are still a lot of 1024x768 users out there: http://www.w3schools.com/browsers/browsers_display.asp -- constraining width to fit on a 1024px screen is fine (don't forget to subtract for the scrollbar).
http://www.useit.com/alertbox/20030825.html
http://www.usability.gov/