100mb fibre optic explained?

[Steve]

I agree with Andy - speedtest.net is the most reliable and is capable of measuring the speeds offered by Virgin (which some others aren't)

You need to rule out everything but the Virgin Line before trying a speed test in order to get a true reflection (Virgin Media support will tell you to do this before they investigate any potential issues)

Eliminate Software Issues: Close all running applications - even better reboot your PC.
Eliminate Wireless Issues: Connect your computer directly to your router using an Ethernet cable and TURN OFF the wireless on your computer
Eliminate Connection Issues: Log in to your Virgin Router and reboot it.

Wait for the router to have fully restarted (give it 5 minutes to be safe) then try your speed test again.

If you're still getting a slow connection, then it is likely that you have a problem so it's time to give Virgin Media a call: 0843 506 9492 and make sure you tell them the steps you've just been through.

It will save you time on the call :-)