Moving from Windows where I'm reasonably proficient, but I'm a Mac Noob. If I was getting a new Win PC first thing I'd do would be to partition the usual stupidly large C: drive, to separate the OS from the user data, so that should a reinstall be needed, the data stays untouched. Or conversely, should something happen to my data, I can get that from backup without affecting system files. Googling shows contradicting advice and no clear recommendations on whether this is necessary, beneficial or even pointless with Mac and some of the advice seems quite old and possibly no longer relevant but I can't tell. If it makes any difference, its likely that at some time I'll be installing Bootcamp or Parallels. So, do the readers of these forums have a consensus on 'best practice' and if it is deemed beneficial, if I don't format at install time will that make it more difficult later or does it make no difference?