There are different kinds of GUID/UUIDs. You have a bunch of version 4 UUIDs:
http://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_.28random.29
Version 4 (random)
Version 4 UUIDs use a scheme relying only on random numbers. This algorithm sets the version number (4 bits) as well as two reserved bits. All other bits (the remaining 122 bits) are set using a random or pseudorandom data source. Version 4 UUIDs have the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is any hexadecimal digit and y is one of 8, 9, A, or B (e.g., f47ac10b-58cc-4372-a567-0e02b2c3d479).