is that you need to establish and maintain a connection to the Internet perchance you need to contact the Zinstall Support Team -- without antivirus and firewall, respectively, enabled.

Maybe a router SPI firewall will suffice, but in my experience it only reduces the risk nominally. If anything malicious is aimed at the computer system, a router firewall is not likely to stop it.

However, I've heard that two routers, one configured as a "gateway" (to which Internet access it cabled) and another configured as a "router" between the gateway and the computer(s) on the LAN, is much more secure.

That said, the Zinstall XP7 application is certainly interesting. It seems to me that it would, basically, be like having two partitions on the same HDD, each of which has a different version of Windows. I suppose that it boots Windows 7 though.