i have the same problem, with my laptop Hp Touchsmart Tm2 2105.
I installed the drivers 8168 from Realtek. It is loaded, and the command ethtool returns :
It looks like if it was in Gigabit modus. But a download test with another PC on my LAn under Windows shows a rate of 130 Mb.
sudo ethtool eth0
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Port: Twisted Pair
Supports Wake-on: pumbg
Current message level: 0x00000033 (51)
Link detected: yes
The Hardware is ok, since the same test, with the sames PCs, but the laptop under Windows shows a download rate of app. 500Mb.