The way I understand it , to "format" means to erase everything. I think you mean to "defrag" the hard drive. I think "system restore" will also cause you to lose things like passwords and maybe even some files & pictures. Better wait for someone more computer smart then me to answer though. I have 2 defrag programs , one under my Norton security program that just does a quick 5 minute defrag and then the one under my Windows admin that takes over an hour sometimes to finish. I collect a lot of pictures through the month (over 1000) and at the end of the month , clean them out(save) to DVD's. I also down load everything in my PC at the end of the month to an external hard drive in case my computer crashes , I can recover everything. It's after I'm done with all that that I do a Window's defrag.