i just got my first Mac the other day and altogether i love it! but theres a couple of things that i just cant figure out how to do. for example, everytime i download something off of a website its on my desktop as a .sit file. i read on a previous thread that i needed to expand the file because it is compressed. so i used my stuffit expander that came with my comp. just to clarify i have an ibook g4 OS X. so after i expanded them i dont know what to do, because i double-click the files and it goes to disk utility, now im completely lost. 