Share 'which elluminate do I need?'

I am interested in participating in some of the events but don't have elluminate software. I went to the site but there are lot of versions. Is the v-room one what I need or just the demo? I will be participating from my home as it is school holidays here in SA and my school will not be purchasing a school elluminate account either. Thanks in advance, Louisa Guest, Hackham East Schools, SA.