I am not aware that it renders "very differently". There are some bug fixes and also new bugs (!) but if you code to standards, your pages should be mostly the same.
I haven't noticed this myself in the standalone version of IE7 I've been testing with. I will look out for colour differences now!
You could always have got that in the past at any time by turning ClearType on in Windows. IE7 sins by forcing it on when it's only meant for LCD screens. Many people are still using CRTs. I do prefer it on my LCDs though.
Right-click on the desktop, select Properties, then Appearance and hit the Effects button. That's the global setting, but I don't know if it also works with IE7.
[edited by: Hester at 10:39 am (utc) on Oct. 19, 2006]