Get default folders in Windows

In order to get any system folder under Windows (I guess from 95 to Vista) by any programming language, you can call function:

HRESULT SHGetFolderPath( HWND hwndOwner,
int nFolder,
HANDLE hToken,
DWORD dwFlags,
LPTSTR pszPath
);
( http://msdn2.microsoft.com/en-us/library/ms647764.aspx )

and pass in the folder you are looking for, such as:
CSIDL_MYDOCUMENTS: My Document
CSIDL_COMMON_APPDATA: C:\Documents and Settings\All Users\Application Data
CSIDL_PROGRAM_FILES: C:\Program Files.

Check the following link for all IDs:
http://msdn2.microsoft.com/en-us/library/bb762494.aspx

Hope these two links can be handy to you.