Fake preloader/loading sign

I have three combo boxes populating with data from an xml file it take a few seconds to load, and i know my users are going to start clicking on it as soon as it shows.

i have it all populating via action script could i just put a white background and then at the end of my code remove it. But my only concern with this, is that it have nothign to do with the load time etc.

a full blown preloader would be cool but not necessary, i dont have to know how to link all the other preloader tuts to what i am doing here
any hints.

Thanks, tom