ipconfig ipconfig /all in VISTA XP Pro.

Go to the Start menu and type command in the box.
Then right-click on Command Prompt and
click Run as administrator.
If a User Account Control window pops click Continue.
2.
At the C:\> prompt type ipconfig .
Then press Enter.
Your IP address, subnet mask and default gateway
will be listed..
3.
If your IP address is 192.168.x.x, 10.x.x.x,
then you are receiving an internal IP address
from a router or other device.
The IP address that the internet sees is that of the router.

[color="RED"If you get a 169.254.x.x address,[/color]
this is a Windows address that generally means
your network connection is not working properly.

If you want more detailed information about your
network connection,
Type ipconfig /all at the prompt

Para two : For XP
Start click RUN type cmd then OK.
A window will open
type ipconfig /all