I have recently bought a computer with Windows 8 (I will call it 'W8'). I would like to keep the install on W8 'pristine' by having it for internal network use only, without access to the internet. I do not have money to buy a separate machine for a firewall to do this, but I thought about using a virtual machine on W8. This VM would have two virtual network adapters and run Linux or BSD with some firewall software. So, I would start the virtual machine, which would then grant W8 access to my home network, but no further; it would control all traffic of W8. W8 itself would somehow route all requests through that VM firewall. I basically want to know: is this even possible? How would I go about setting this up?
I hope you are doing this out of curiosity, because:
Keep in mind that a cheap ARM-based computer can cost as little as 20€.