You could read the path from the registry: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\* where * is one of those Keys:
- Local AppData (
C:\Documents and Settings\USER\Local Settings\Application Data)
- Local Settings (
C:\Documents and Settings\USER\Local Settings)
- AppData (
C:\Documents and Settings\USER\Application Data)
Note: Those example paths are from an english Windows XP installation