The search order varies depending on the state of SafeDllSearchMode.

Windows DLL search order if SafeDllSearchMode is enabled:

• The application directory
• The system directory (as returned by GetSystemDirectory())
• The 16-bit (!) system directory
• The Windows directory (as returned by GetWindowsDirectory())
• The current directory (!)
• The system PATH (!)

Windows DLL search order if SafeDllSearchMode is disabled:

• The application directory
• The current directory (!)
• The system directory (as returned by GetSystemDirectory())
• The 16-bit (!) system directory
• The Windows directory (as returned by GetWindowsDirectory())
• The system PATH (!)

Note that it seems more-or-less impossible to determine what DLLs an application is searching for without having SYSTEM access already (so tools like ProcMon can be run).