Network / Sharing :: Broadcom NetXtreme Connected To LAN But No Internet

I've just bought an HP N54L which has a Broadcom NetXtreme NIC. Bit of a bargain and since I've never had the slightest issue with my HP N40L (running Server 2008 R2) I decided to get a new one

I did a bit of research on the hardware and so made sure I flashed the BIOS to the latest rev. I then installed Windows 8 Pro 64 on it - the installer went smoothly with no hiccups. It received an IP via DHCP as well as the default gateway address. I can see my other devices on the same subnet

My neighbour and I share one internet connection, him on (eg) 192.168.0.0/24 and me on (eg) 192.168.1.0/24.

My Router is 192.168.1.1 and his Router is 192.168.0.1. My Router handles all traffic from my subnet to his. His Router handles his own kit plus the link to the internet. Neither Router is set to restrict access by hardware (eg: by MAC)

While my N54L could see all the devices on my subnet, and I could browse it's shares from one of my other computers, it cannot access the internet. I do not receive a ping back from my neighbours router

I have temporarily disabled the Windows Firewall and any other protection during testing. Windows 8 is a clean build with no 3rd party software on it as yet...

I have tried using netsh to reset the tcp stack and ipv4
I've checked all routes on the N54L and they match all my other devices
I've double checked both my Router and my neighbours Router (I have administrative access to it)

I tried the default driver on the Windows DVD, also the latest for Windows 8 on Broadcoms website as well as (just to test) the latest for Server 2012. Tried setting the network as both Public and Private (via a re-install since it wouldn't let me swap type). Tried both DHCP and static IP. I only have the 1 Default Gateway, which is my own Router

Whatever I do, this PC seems stuck in it's own subnet

I've checked the network cable too which works fine

My other kit (which all works fine) is a mix of: Server 2008 R2, Server 2008, Server 2003, Win7 64, Win7 32, XP SP3, Linux of various flavours, and Android

So my suspicion is that this is a Windows 8 "feature" ? Any particular settings within the NIC itself?

I may stick my Server 2k8 R2 build on it just to test my theory, and prove that the PC with it's NIC works fine and that the problem is limited to Windows 8. I bought Windows 8 because I want Hyper-V and want to tinker with Storage Spaces.