Re: Reformat vs. Defragment
Generally, it organizes the clusters so that everything is properly grouped. When you delete files, uninstall this and that, remove and add this, you end up with a bunch of messed up clusters where it's not continuous anymore. Search will take longer because the hard drive has to find the data. Defrag puts everything together in a conitnuous fashion. Think of road repairs. Lots of potholes, dips, cracks, bumps slows the car down. Repave the street and cars go faster. Ok, maybe not the perfect example but you get the concept.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?