Hi ,

I have set up a network, which I'm a little confused how it is connecting
together. I'm not complaining but it has just been a little too straight
forward so far. Here is my network so far:

Cable Modem (Broadband connection)
10/100mps Broadband 4 port switch / wireless router -------- XBox360 (Wired
Connection) and Laptop with Win XP Pro SP3 (Wireless connection)
85mps Ethernet Home Plug X2
10/100mps Ethernet Switch Gigabit port (8 ports)
PC with Win XP Pro SP2

I connect an Ethernet cable from my cable modem to a wireless 4-port
switch/wireless combined router. I have a laptop connecting wirelessly to
the 4-port switch/wireless router and a Xbox360 connecting wired to the
4-port switch/wireless router. The 4-port switch/wireless router uses DHCP
and both laptop and Xbox360 connect via the router to the Internet fine.
I have a networking over mains kit that I have connected 1 plug to the
4-port switch/wireless router and the other to a 8-port switch that sits at
the other side of my house. I have connected a PC to the 8-port switch and
it connects to the Internet (via the 8-port switch, networking over mains
plugs and the 4-port switch/wireless router)

What I am confused about is how networking over mains can act as a link
between the 8-port switch and 4-port switch/wireless router to not only gain
Internet access but act as an internal workgroup? Will there be any
limitations I need to be aware of? The laptop and PC are set in a workgroup,
they are both set for file and print sharing and I can ping both PC and
laptop from/to each other. All is well but I'm just confused how the
networking over mains enables this all to happen. I'm new to networking over
mains and not too up-to-speed with how it works apart from the 40 I spent
was worth it so far.

Any help will be greatly appreciated.