You know what, it just dawned on me that at one point I had my IE7 ClearType disabled because I didn't like it's smoothing effect. I don't know if that setting is carried on to Chrome or not.
I'm on XP + Chrome.
I'm on XP + Chrome.
What it sounds like the white drop shadow did in your case was simply force ClearType on for that text.
Found a tool that optimizes the contrast http://www.microsoft.com/typography/ClearTypePowerToy.mspx