The MBA would likely meet your needs and 8GB of RAM should be sufficient for running a VM.
Also, you may have better success in attracting responses to your thread, and you'll make your thread easier to find for those browsing the forum for the same answers, if you change your thread title to something more descriptive, such as "Buying advice needed". To do so, click the "Edit" button on your original post, then click "Go Advanced" and you will see where to edit the thread title. Your current title sounds like the topic being discussed is about computer security and forensics, not about your buying decision.