Securing home network from domain

[djg85]

I've recently finished wiring the flat up with some CAT6 and have an ESXi box running a few VMs (including my Unraid media storage). I purchased a domain a while back and would like to point this to one of the VM's so I can play about with a new Server 2012 install and remote access the server. I'm using DynDNS to update the domains records to point to my router which will then forward on to the IP for the applicable server. I'm just wondering what would be the best way of securing this all so this is kept separate from the rest of the network? Just a bit paranoid about something potentially causing issues with my media storage. Don't really know that much about networks so unsure on the best way of separating the VM for the server from the rest of the internal network (don't think a DMZ would be the best option here). Currently with Sky and have one of their rubbish Sagem routers.