I am an Installing Machine
Welp, my dream of a VM within a VM will alas remain unfulfilled. I really couldn't get Vagrant to boot the Discourse VM without hanging.
I've been hesitant about installing Ubuntu on my laptop, but I finally gave in and decided to dual-boot Ubuntu and Windows at Kurtis's suggestion. Learned a bit about HD partitioning and boot loading. Bye, Linux VM and LinuxLive USB!
I've set up my Linux dev environment yet again (probably 10th time in the last month? here's to repetition), and will try to get Discourse running by tomorrow.