Go to start and then click Run (if you are using Windows XP) and then type "getmac" there. You will be given the Mac Address of your system. If you are using Windows 7 or Vista, you can directly type the "getmac" command in the "search" field after going to Start Menu. You will find the physical address in the left column of what is shown on the screen. Alternatively, you can use Jags method regardless of which operating system you use. Just type "ipconfig /all" in the run or search field that you get after tapping the Start Menu.
Please note that physical address is same as the Mac Address of your PC.