The Win32 API has the function Sleep(ms : longint); for this purpose.
If you are working with D1, use the following function - it waits for a given amount of milliseconds.
It allows the current application and other applications to process incoming messages:
procedure Delay(ms : longint);
var
t1 : longint;
begin
t1 := GetTickCount;
while (GetTickCount - t1) < ms do
Application.ProcessMessages;
end;