Hi Craig,
I know what you did because I looked at the html and css page before I wrote in the first place. The validator matters not , especially when browsers comply as they choose with css. I mean, it's nice that it validates, but the way you are doing this is not good over the long haul. Modify the rawpaleo.css, do not give that particular html page its own sheet. That is the equivalent of building a new house just because you want to put a deck out back. Better to make the deck on the house you have. The ONLY time you want a new sheet is when the page has totally different styles.
You are styling html tags you don't even need (nor should you want to place them all over in the html page). CSS should make your life easier, not harder. Those tags are competing with styles laid out for links in any paragraph on the css page. In IE7 the graphic is way out there to the right, and not underlined, and it looks like doo doo. The underline is shown on the hover on that browser only, whereas in Firefox it's always there and thus is double underlined. I highly recommend that you delete the graphics and just make a note that all links are external at the top of the article under the title of it. They really don't look good in the paragraphs anyway. Too much clutter.
Do this in rawpaleo.css if you must have them there:
.external {all the original stuff for the ones used in headers}
.externalp {change the margins when you have external links in paragraphs}
Get rid of the other style sheet! Keep your back ups, good deal. You may well want external links in paragraphs elsewhere, and why should you have to link to an entire new style page when most of it is copied from the first one anyway (all layout, and all that jazz). And for heaven's sake, git rid of the underline tags. THAT IS A DEPRACATED TAG AND WILL NOT BE SUPPORTED IN HTML MUCH LONGER!!! You must think in terms of css whenever possible; and if you don't, you will end up in deep doo doo about this sort of thing in no time. It is not some wysiwyg software where html tags are a fun side benny. You have to learn css and deal with its rules, not try and fudge old, crusty html tags in a css document. Believe me, there is a big difference. It took me some time to understand css and how different browsers deal with it. I have been working with it part time for 5 years and still I have stuff to learn. It is something that if you don't know what you are doing, you will cause major problems that will be very hard to find and fix. And who knows what it looks like in the wretched IE6?
One day at a time, eh? I suggest you get ocd about learning css inside and out. And make sure you avoid, whenever possible, depracated html tags.