Creating a New Partition on a Hard Disk in windows 7 & 8 without formatting the computer

The Disk Management tool provides a simple interface for managing partitions and volumes.

Here’s an easy way to create a new partition on your disk.
1. Open the Disk Management console by right-clicking My Computer>Click Manage>Select Disk Management

2.In Disk Management’s Graphical view, right-click an unallocated or free area, and then click New Simple Volume. This starts the New Simple Volume Wizard. (Note: If you need to create unallocated space, see the Tip Easily Shrink a Volume on a Windows 7 Disk for information on how to do this.)

3. Read the Welcome page and then click Next.

4. The Specify Volume Size page specifies the minimum and maximum size for the volume in megabytes and lets you size the volume within these limits. Size the partition in megabytes using the Simple Volume Size field and then click Next.

5. On the Assign Drive Letter Or Path page, specify whether you want to assign a drive letter or path and then click Next. The available options are as follows:

 Assign The Following Drive Letter Select an available drive letter in the selection list provided. By default, Windows 7 selects the lowest available drive letter and excludes reserved drive letters as well as those assigned to local disks or network drives.
Mount In The Following Empty NTFS Folder Choose this option to mount the partition in an empty NTFS folder. You must then type the path to an existing folder or click Browse to search for or create a folder to use.
Do Not Assign A Drive Letter Or Drive Path Choose this option if you want to create the partition without assigning a drive letter or path. Later, if you want the partition to be available for storage, you can assign a drive letter or path at that time.

6. Use the Format Partition page to determine whether and how the volume should be formatted. If you want to format the volume, choose Format This Volume With The Following Settings, and then configure the following options: 

 File System Sets the file system type as FAT, FAT32, or NTFS. NTFS is selected by default in most cases. If you create a file system as FAT or FAT32, you can later convert it to NTFS by using the Convert utility. You can’t, however, convert NTFS partitions to FAT or FAT32.
Allocation Unit Size Sets the cluster size for the file system. This is the basic unit in which disk space is allocated. The default allocation unit size is based on the size of the volume and, by default, is set dynamically prior to formatting. To override this feature, you can set the allocation unit size to a specific value. If you use many small files, you might want to use a smaller cluster size, such as 512 or 1,024 bytes. With these settings, small files use less disk space.
Volume Label Sets a text label for the partition. This label is the partition’s volume name and by default is set to New Volume. You can change the volume label at any time by right-clicking the volume in Windows Explorer, choosing Properties, and typing a new value in the Label field provided on the General tab.
Perform A Quick Format Tells Windows 7 to format without checking the partition for errors. With large partitions, this option can save you a few minutes. However, it’s usually better to check for errors, which enables Disk Management to mark bad sectors on the disk and lock them out.
Enable File And Folder Compression Turns on compression for the disk. Built-in compression is available only for NTFS. Under NTFS, compression is transparent to users and compressed files can be accessed just like regular files. If you select this option, files and directories on this drive are compressed automatically.

7. Click Next, confirm your options, and then click Finish.

The Windows 7 Disk Management tool will now show the space configured as a new partition.