[meld51]

Google "Network Magic". It's a paid for software now owned by Cisco I think, with a free period to start with. It maps your net and troubleshoots problems, but once you get used to it it times out and you have to buy a licence. Earlier versions were free so I think they've sold out now. Still it's good.

As an alternative there is Spiceworks which is free. I've just started using this so I won't recommend it yet...but it looks like a useful network utility