Network limitations of Vista Home Premium ?

I bought a Dell laptop which came with Vista Home Premium.
When I do not travel, I have a wired network at home and of course I want to
use it with my laptop.
I can see the shared resouces on the internal network, so that's fine.
However, I do not manage to make the Internet work on my laptop.
The router which connects tot the broadband ASDL line has the address
192.168.0.254 internally. I give the laptop an address like 192.168.0.7 and
refer the DNS server and gateway to the router. This works perfectly with my
desktop PC runnung Vista Ultimate. With my laptop (Vista Home Premium), I
just can't get the same thing right. The only way I found to be working is
to connect the laptop directly to the modem but then of course the Internet
is unavailable for the rest of the network.
I would like to know if this is a known limitation and due to the reduced
functionality of Vista Home Premium, compared to Vista Ultimate?
Has anyone got a trick to make this work anyway? This limitation is very
annoying here.