I really don't want all of my current data put into an archive folder and the simple "Upgrade" installation option of Leopard seems most practical for me. 2 questions - 1) Will choosing "Upgrade" over a clean install affect performance? I have a C2D MBP. 2) I notice that the required disc space for installation is 9GB. If I choose to upgrade "over" Tiger like I mentioned earlier, will some of Tiger's OS data be erased, "cushioning" the amount of disc space used instead of just sucking up a full 9 gigs?