Completely unrelated to the Linux install. What protocols do you have enabled in Windows? I've seen a lot of IPv6 "supported" systems that chew up a lot of bandwidth just trying to negotiate.
If Linux works, your hardware is fine. Remember, whatever speed test you do only manages traffic that's going outside your LAN. Doesn't account for inside. Any home sharing will chew it up too. You need some sort of internal tool, like Wireshark, the can analyze the traffic on the adapter and let you know what's eating up the bandwidth.
Have your run even basic performance monitors in Windows?
If Linux works, your hardware is fine. Remember, whatever speed test you do only manages traffic that's going outside your LAN. Doesn't account for inside. Any home sharing will chew it up too. You need some sort of internal tool, like Wireshark, the can analyze the traffic on the adapter and let you know what's eating up the bandwidth.
Have your run even basic performance monitors in Windows?
