Below is a short guide to partitioning a computer's hard drive.
Partioning with a new OS installation.
Partitioning as part of an OS installation
If the new hard drive is also the one that the OS is being installed on, then partitioning is part of the installation. If the OS is Linux or Mac OSX, then just let the defaults go through and the partitioning will be automatic.
How to split the disk? For Windows, I prefer to split disks into two partitions. Therefore, rather than accepting the default, when the installer asks about partitioning, I choose custom. Amount Assuming the disk is 100gb or more, I would put 35gb for windows and 65 for data. When you install applications, choose 'Custom installation' and install them onto your 65gb partition. Also store your documents on the 65 gb partition.
This means a windows installation can wipe the 35gb partition with minimal effect on data.
NOTE: If you haven't configured windows to store your profile on the 65gb partition, then you will lose some data unless you have backed it up.
Partitioning an existing disk
There are several reasons why you might need to repartition an existing disk.
Re-installing the Operating system
As with a fresh installation, just use the partitioning options that the OS gives you when you go through the installer.
Splitting an existing disk
This is where you might want to split data between two partitions, say to create a space for specific data (say keeping photographs separate) or to separate data from the Windows partition.
Shrinking the existing partition Assuming the entire disk currently contains a partition, firstly you will need to split the data using a partition utility like Partition Magic to shrink the existing partition. Next, you need to partition the new space into the correct type of partition. For any modern version of Windows, you attempt this through the Control Panel. In Administrative tools, go to Computer management: there is an option for disk management.
Click on that and you can see all the partitions and empty space on your hard drives. Select the empty space and right click and select "Create partition". Tell it to create a ''ntfs" partition and then format it.
Mac Operating systems In Mac OS you use the Disk Utilty. The principle is the same, but this time format the space as mac OS extended, not NTFS. In both cases, the new partition should now be available for use. WARNING
Remember that formatting destroys ALL data on the disk and recovering data after a partition is nearly impossible, and likely to cost a lot of money. If in doubt, take your computer to a local computer shop for help and advice.