This is more curiosity than issue or problem -- But I'm wondering where the bits and pieces of canceled downloads go. If I'm downloading something (say a podcast, or a PDF), and then decide against it partway through & hit cancel - what happens to the already-downloaded bits? I assume they aggregate somewhere and need occasional throwing out? No? I guess another way to ask a related question is 'Are there routine computer cleaning steps a mac user should be doing - the way windows users defrag the hard drive?' Maybe there's a better place to ask the question, but I don't know it. Thanks.