Help please with WAIK & Virtual Pc2007 (621 exam)

I have just purchased a 3.5" Usb Hdd case and put a 20Gig HDD and I have installed Virtual PC on my Vista Ultimate computer so I can study for the 621 exam upgrade but I am having difficulties getting the Virtual PC to work. I followed the instructions in the book to install the WAIK image on the target HDD and then boot the the V Pc (Virtual PC). Does anyone know where I can get clear instructions on dealing with Virtual Pc. I need to practice for my 621 exam.