help

Open LiveSplit, go to Edit Layout, then Layout Settings and check Always on Top. You also need to play MW2 on anything but Full Screen mode, so use Windowed. I hope this helps

Also, for to put the steam copy of the game into window mode (As mine doesn't have a option for it in the settings) head over to where the game is installed to, head into the players folder, then config.cfg find this line (ctrl+F in notepad is your friend) "seta r_fullscreen" (without quotes) then change the 1 to a 0 and then it should be in windowed mode next time time you boot the game, providing that you saved the config edit :)