What are the major changes in the 'Guide to PMBOK third edition?. Is it totally different from PMBOK guide 2000?
I will say that 'Guide to the PMBOK third edition' is more reader friendly than the earlier versions. The third edition is is structured to give more emphasis to the process groups. Chapter 3 is renamed as 'Project management processes for a project' is extensively revised and is moved to a new chapter titled 'The standard for project management of a project'. In the third edition, seven processes have been added, thirteen renamed and two deleted. The terms 'facilitating processes' and 'core processes' are no more used. The project management processes are still grouped under;
- initiating process group
- planning process group
- executing process group
- monitoring and controlling process group
- closing process group
To make it clearer - if you have done your preparation well using the 'Guide to PMBOK third edition' and write the exam based on PMBOK guide 2000, your probability of success will remain the same, if not more! I think, that explains it better.