In Vista, the default text-to-speech voice is Microsoft Anna - English (United States).
Is there any text-to-speech voice in German or in other languages ?
There is a specialized voice for speaking chinese, Microsoft Lili.
As far as I am aware the only way to get her would be to install the chinese language pack, and then it should still be available when you switch the system back to english. I have heard (no personal experience) that Lili is actually superior to Anna for english voice output due to having a more clear pronounciation.
Alas, I haven't seen any other microsoft-given voices for Vista/7. All third party.