Need some advice.

Ive got a client with an internal network and a public room used for training purposes.  The requirement is both networks going through 1 ADSL Gateway with no communication between the two networks.  Theyve allready had 5 different local IT guys look at this and fail.

Its pretty clear to me that they will need to be on two seperate subnets, but how to route the traffic without allowing any file access between the two networks.

Would the solution be to have the existing ADSL Router and use 2 Non ADSL routers to manage to and from different subnets.  The router being on its own subnet and public and private network being on 2 different subnets.  If so could someone recommend a cheap and chearfull device for job suitable for a small office, (Waits for Mark to quote Cisco model lol)

Someone said to me that Layer 2 Switching would do the job but my understanding was that only Routes can manage traffic between different subnets. No?  The Cisco training is up there some where.

Oh I know it will work, I was just wondering if there was a simpler way or if anyone could recommend what kit to use.

All you need is a single layer 2 switch, and set up 2 VLANs. Simple.

Or replace your router with a proper router, and use 802.1q tagging or 2 FE ports on it for the seperate networks.

Decent cisco router FTW. Or if you need a dirt cheap solution some of the Allied Telesis layer 2 switches have some awesome vlan features.