I've always been an advocate of trying to prepare yourself using the official resources that VMware make available - the exam blueprint tells you what aspects of vSphere 5 you will get tested on, the exam format, number of questions, time limit, and the scoring system. The exam blueprint makes references to the official vSphere 5 documentation, which VMware validate the exam items against, and the mock exam gives a decent indication of the exam format. The VCP community forum is an excellent way of asking VCP5-related questions and getting furter information.
VCP5 homepage
VCP5 exam blueprint
VCP5 mock exam
VCP community forum
vSphere 5 documentation
Something that VMware don't publish is an expanded exam blueprint that includes all the relevant study notes, however there are a number of sites where people have done exactly that - be careful when using these study notes in case they're not accurate in comparison to the official documentation.
Forbes Guthrie's vReference documentation notes for vSphere 5
Prep Guide for VCP5.0
Andre Mauro's vInfrastructure VCP5 notes
There are a number of people in the VMware community that write and publish their own practice questions, normally as part of their own preparations - it should be noted that these do not necessarily indicate the types and styles of questions you will get in the real exam, and the accuracy of these practice exams cannot be guaranteed either.
Robert Stothard's VCP5 practice questions
Simon Long's VCP5 practice exams
Paul McSharry's VCP5 practice questions
To finish, here are a couple of exam experience blog posts from people that have taken the exam themselves - I'll post my own review once I've taken the exam myself!
Eric Sloof's VCP5 exam experience
Brian Tobia's VCP5 exam thoughts and experience
Best of luck....!
