If your really wanting as much space as possible and don't want to suffer any slowdown, you could always try one thing. I don't remember if I saw it here or on se-nse, but I remember there being a thread a while back about how you could format your memory card using the smallest allocation possible, and even though you physically wont see an increase in space in my computer, it does allow you to put more things on it (depending upon the size of the files. I guess it's more noticable with small files rather than larger files)