There are a lot of tools around to monitor your network and NICs, but I found a single line of PowerShell code can list your network cards (local and remote as well) and their bandwidths:
Get-WmiObject -class Win32_PerfFormattedData_Tcpip_NetworkInterface |
Select Name, CurrentBandWidth |
Format-Table
@{Expression={$_.Name}; Label="NIC" },
@{Expression={$_.CurrentBandWidth/ 1000000 }; Label="MBit/s"}