I have just done my 70-450 today (841/1000). My advice it to buy the pocket admin guide and buy the 70-432 MS study book. It gets a slating, but I thought it was good if coupled with the relevant msdn sections. If you can though, try and create some VM's and create your own set of servers and practice mirroring, clustering etc. It really helps in the exam if you cover all bases as the questions are spread very wide. Paul.