Ok. I was looking around at some css sites and came upon a site with css tabs that also mentioned the "IE6 Flicker" problem:
Quote Originally Posted by http://superfluousbanter.org/archives/2004/05/navigation-matrix/#comment15
The damn flickering is something the IE team should fix, honest, too many designers are suffering from this obvious flaw. That said the flickering in IE6 will only occur in one instance. IE6 has an assortment of options to check for newer versions of stored pages, that are located under Tools » Internet Options… » Temporary Internet Files » Settings. In that list you can choose between:
- Every visit to the page
- Every time you start Internet Explorer
- Automatically
- Never
The automatically option is checked by default. Most designers set this option to every visit to the page to make sure they’re not viewing a cached version (when testing). When the latter setting is used it will flicker no matter what you try, IE6 will load the image again each time you hover, and thus result in flickering, unfortunately setting a background image the the list element itself does not solve the problem. But my guess is that just a small percentage is using these settings (it just happens to be the small percentage looking at this and other examples, probably.) With all the other settings no flickering occurs, to my knowledge
So it looks like its for people who have "NEVER" store pages .. which should be very few people.

He also figured out a solution... but its too much work to bother with since IE7 fixes the problem (stored pages ignores the tab images which are cached). Essentially I would need to create new images to load in the background with the same color as the tab images so that when the tab image changed it would show a duplicate color in the background.