ipconfig /all
Find the entry labelled "Ethernet adapter Local Area Connection" and read off the Physical Address. This is the MAC address you need.
Do not read off the Physical address from the entry labelled Wireless or Virtual or Tunnel.
C:\>ipconfig /all
Windows IP Configuration
Host Name . . . . . . . . . . . . : Bert
Primary DNS Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : Yes
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . :
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek RTL8139(A)-based PCI
Physical Address. . . . . . . . . : 00-48-54-82-60-0E
DHCP Enabled. . . . . . . . . . . : Yes
IP Address. . . . . . . . . . . . : 128.100.2.164
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 128.100.2.254
DNS Servers . . . . . . . . . . . : 128.100.2.251 128.100.2.250
Primary WINS Server . . . . . . . : 128.100.2.31
Secondary WINS Server . . . . . . : 128.100.3.248
Therefore, the MAC address is:
00-48-54-82-60-0E