If you have to get comfortable on the vmware training session , make sure you are already comfortable with the normal networking concepts. A good understanding of TCP/IP networking and Microsoft family of networking OS makes you an ideal candidate. Your skills with command prompt environments in general and linux commands in particular will be nice The more practical skills you have in IT infrastructure management , the better. Hope you are already aware of the basic hardware aspects, memory management concepts , network cabling , and the basic routing skills. the more you know about the switching environments and terms , the better.