displaySwitch.exe code replacement for windows (pre windows 7) - delphi

Question

I'm writing an app I'd like to be backwardly compatible to some extent on XP, or at the very least windows vista.
EDIT FOR CLARITY: I need to be able to do what the first code snippet below does, but in XP. "Does anybody know the best approach to take under XP, given the functions aren't available in USER32.DLL.?"
My initial prototype code on windows 7 just called CreateProcess to start up displayswitch.exe, which is deployed with windows 7.
if you are not familiar with it, it's a handy little utility that is what gets invoked when you press the windows key and the letter P. you can read more about it here.
while this was adequate, i subsequently needed to sense the current state (eg internal vs external or extend vs clone), so i have now coded up a winapi solution that works well on windows 7 (and i presume 8). it involves making calls to SetDisplayConfig and QueryDisplayConfig in User32.DLL
The pertinent section of it is here (minus the many, many structures i had to hand craft in pascal code from the original klingon).
function getTopology : DISPLAYCONFIG_TOPOLOGY_ID ;
var NumPathArrayElements,
NumModeInfoArrayElements : UINT32;
var PathArrayElements_Size,
ModeInfoArrayElements_Size : UINT32;
error : Longint;
paths : PDISPLAYCONFIG_PATH_INFO_array;
info : PDISPLAYCONFIG_MODE_INFO_array;
begin
NumModeInfoArrayElements := 0;
Result := DISPLAYCONFIG_TOPOLOGY_EXTERNAL;
inc(result);
error := GetDisplayConfigBufferSizes(QDC_DATABASE_CURRENT,NumPathArrayElements,NumModeInfoArrayElements);
case error of
ERROR_SUCCESS :
begin
PathArrayElements_Size := sizeof(DISPLAYCONFIG_PATH_INFO) * NumPathArrayElements ;
ModeInfoArrayElements_Size := sizeof(DISPLAYCONFIG_MODE_INFO) * NumModeInfoArrayElements;
GetMem(paths,PathArrayElements_Size);
try
GetMem(info,ModeInfoArrayElements_Size );
try
error := QueryDisplayConfig(QDC_DATABASE_CURRENT,NumPathArrayElements, paths,NumModeInfoArrayElements, info,result);
case error of
ERROR_SUCCESS :;
else
Result := DISPLAYCONFIG_TOPOLOGY_EXTERNAL;
inc(result);
end;
finally
FreeMem(info,ModeInfoArrayElements_Size );
end;
finally
FreeMem(paths,PathArrayElements_Size);
end;
end;
end;
end;
function setTopology ( top : DISPLAYCONFIG_TOPOLOGY_ID) : boolean;
var flags : dword;
begin
result := false;
flags := DecodeDISPLAYCONFIG_TOPOLOGY_ID_SDC(top);
if flags <> 0 then
begin
result := SetDisplayConfig(0,nil,0,nil,SDC_APPLY or flags) = ERROR_SUCCESS;
end;
end;
Since these functions don't exist in XP (as far as I know), I am looking for a stable way of achieving a similar thing in XP. whilst i am coding in Delphi, it's not necessary that the solution be presented as such. i am quite happy to just look at how it's done, or read a description of the appropriate steps, and implement it myself.
(removed full listing as it was confusing the issue as it did not appear like a question)