System Font (Segoe UI)

Segoe UI (pronounced, "SEE-go") is the new Microsoft® Windows Vista™ system font. It is designed specifically for user interfaces and is optimized for ClearType font technology.

Segoe UI:
Improves consistency in text styles across all languages.
Is optimized for ClearType, which is on by default in Windows Vista. Segoe UI is less readable without ClearType enabled.
Has the standard font size increased to 9 pt. to accommodate for better layout and readability for all languages.
Has a new set of themed font styles that can be referenced through the Aero theme file.
Contains currently the Latin, Greek, and Cyrillic characters. Microsoft will continue to develop, add character sets and support this font.