If you mean that you want the transition to be immediate (no animation), then you can set the 'speed' option to 1 (that's one millisecond). The'speed' option is the animation speed, just like the second parameter of a normal animate() function.
Or you may mean that you would like an animation which does not involve an opacity fade, in which case you can alter the 'animation' parameter to {'height':'show} which will animate the height only. Hope this helps. Joel Birch.