It was a fluke!
When I installed Windows 7 on Parallels, it was an OEM System Builder license. This is why moving it around from Parallels to VMware to VirtualBox upset Windows Activation; you’re only allowed to use that license on the first “motherboard” you install it on, in this case the virtual motherboard Parallels gave the virtual machine.
I’ll look into other options for running MSN. First of which being to try installing it into a ReactOS VM. All the versions of MSN I’ve tried won’t work in Wine, so I’m skeptical.