I've changed my VS2005 color scheme to a funky black-background scheme that I found on the net (and then tweaked a bit). I hadn't noticed this before, but today while in the HTML editor the text on the currently selected line looked absolutely horrible. I suspect that it's the antialiasing that is assuming things about my color scheme. Whatever it is (could also be ReSharper but I can't tell) it's extremely annoying and may cause me to switch my colors again.
Update: Turns out the issue _was_ ReSharper. It has a feature called "Highlight current line". I turned that off and problems go away! I've filed a bug with JetBrains.