It depends on the language selected.
http://mlang1.osaka-gaidai.ac.jp/~tagengo/multi/win_font_list.html shows a list for most versions and languages.
I know that font loading really labors any Win system in terms of memory hogging and startup times. I recall seeing somewhere on the Micro$oft site, the minimal fonts req'd for XP. Does anyone have that list? And why doesn't WinXP (and now Longhorn) have some kind of font maintenance feature. I use Typograf and it works great.