Best Answer Karl L. , 12 December 2012 - 04:15
A GPT partition table has many advantages over a MBR, so long as your operating system supports it. It is only a necessity, however, if you need a partition larger than 2 TB. Besides the partition size limitation, the only other thing you need to consider is comaptibility: you must have 64-bit Windows Vista or newer to read the partitions on the disk.
Check out Petri's GPT vs MBR Disk Comparison article. It is very well written and goes into much more detail than I can. Go to the full post