In Windows 7 systems we find two different partitioning systems. These are the Master Boot Record (MBR) and the Globally Unique Identifier Partition Table (GPT) styles. While MBR is supported by all versions of Windows, GPT is only supported on Windows Vista, Windows 7, Windows Servers 2003 and 2008, and 64-bit versions of Windows XP. GPT offers several advantages over MBR such as, it can support up to 128 partitions while MBR supports only four, GPT is more reliable as it is aware of the modern disks geometries, GPT supports larger partitions – up to 18 Exabytes in theory and uses primary & backup partition tables for redundancy.
When using GPT partitions it is worth noting that larger partition sizes can have side-effects such as, take longer to check (running ChkDsk) and they are not compatible with all operating systems! Also, to boot from a GPT disk, the computer must support the Extensible Firmware Interface (EFI). Remember, that all BIOS based systems must boot from an MBR disk. Removable media cannot be partitioned with the GPT style.