I'm also a fan of Segoe UI, which (as far as I can tell) is actually used in the Vista dialogs more frequently than Calibri. Unfortunately Calibri doesn't look

I'm also a fan of Segoe UI, which (as far as I can tell) is actually used in the Vista dialogs more frequently than Calibri. Unfortunately Calibri doesn't look great when it's used in small sizes so I tend to use Segoe as a small-size alternative.