ProcessID to Filename

Yes, this old chestnut ...

I'm doing the usual stuff ... enumerate processes and then I want to try to
get a fully pathed name to the executable, so I use :

OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_VM_READ, false,
ProcItem.th32ProcessID);

to get the Process handle which I then use with GetModuleFilenameEx to get
the actual filename.

Problem ... when run using a non-administrative account (on XP), OpenProcess
fails.  I've tried :

function EnableProcessPrivilege(Privilege : string; Enable : boolean) :
boolean;
const
  PrivAttrs : array[boolean] of DWORD = (0, SE_PRIVILEGE_ENABLED);
var
  tpResult  : boolean;
  Token     : THandle;
  TokenPriv : TTokenPrivileges;
begin
  Result  := true;
  if (Win32Platform = VER_PLATFORM_WIN32_NT) then begin
    tpResult  := OpenProcessToken(GetCurrentProcess, TOKEN_ADJUST_PRIVILEGES
or TOKEN_QUERY, Token);
    if tpResult and LookupPrivilegeValue(nil, PChar(Privilege),
TokenPriv.Privileges[0].Luid) then begin
      TokenPriv.PrivilegeCount            := 1;
      TokenPriv.Privileges[0].Attributes  := PrivAttrs[Enable];
      Result  := AdjustTokenPrivileges(Token, false, TokenPriv,
SizeOf(TokenPriv), PTokenPrivileges(nil)^, cardinal(Pointer(nil)^));
      CloseHandle(Token);
    end; {if}
  end; {if}
end; {EnableProcessPrivilege}

EnableProcessPrivilege('SeDebugPrivilege', true);

... to no avail ... any ideas ?

Thanks

Andrew