Will re-installing the OS automatically re-format the hard drive?
It depends on whether you have partitioned your hard drive 1. If you have, then no need to format the whole hard drive. Only the partition in which you have the os installed needs to be formatted to install a new OS 2. If you have not partitioned your hard drive, then I am afraid yes, you will have to completely erase everything on your hard drive to install a new OS You don’t have to format the HDD / Partition first to install a new OS. When you boot from a CD, then the CD will format the HDD / Partition before it installs the new OS Good Luck!!