Nope it wont work. I have a device that I will sell to you for only 10.000 Euros

But seriously, 90% or greater of electronics produced in the past 10 yrs will handle 220-240v power with no problem. I have yet to see a laptop power supply that has a switch that needs to be flipped. With that being said, quite a few desktop do have a switch that needs to be repostioned for 220-240v.
All you need is a plug adapter. The two blade style to the 2 round plug style. I bought mine at radio shack because that is the only place I could find that sells the single compact version and they are only about $2.
Ethernet is ethernet...same plug. RJ-45

Just don't go plugging a US hair dryer into a Euro socket.....bad things will happen. Most small kitchen appliances in the US cannot handle 220-240 either.