The Network Card is rated for 1GB Transmissions Speeds but your LAN cabling may not be able to cope with the speed. If you use the standard cabling that Virgin Provide it will only go at 100Mbps. You need to get your hands on a Cat6 Lead (if you don't have one, check the wiring as it says what kind it is) and then plug that in from the router to the PC.
If you use a Powerline Adapter that uses Electrical Wiring please be aware the speed is not guaranteed. I'm on M500 but with the Powerline adapter and a CAT7 Lead, I get 170mbps on Speed Tests.
Try Sam knows Speedtest and Fast.com - multiple sites are better for gauging what your speed actually is.