Perhaps instead of using the interesting random generator you've implemented, you could just use RandomRange? Also, the repeats and result really aren't necessary. The only thing that can come from repeat..until is jerking the mouse around randomly multiple times, which doesn't seem very humanlike. As for the result, mouse movements are generally procedures.
Try something like this:
Simba Code:
procedure MMRandom;
var
x, y, rx, ry:integer;
begin
GetMousePos(x, y);
rx := RandomRange(-700, 700);
ry := RandomRange(-450, 450);
MMouse(x + rx, y + ry, 0, 0);
Wait(250+Random(750));
end;
If you want to get fancy you could add things like:
Simba Code:
procedure MMRandom(xRange, yRange: Integer);
...
rx := RandomRange(-xRange, xRange);
ry := RandomRange(-yRange, yRange);
...
EDIT: Whoops, thanks Le Jingle