Sunny,
Win95/98: winipcfg
NT/2000: I always use netstat /r but there's got to be a better way
I also know how to get this programatically within web apps, but, there's probably a good way to get it with an API call for non-web apps.

I would do a search here to find other responses to similar questions if I were you..

>Sorry For My Poor English..
>I Will Make a Comparison Between My IP Address And Server IP Address.
>I Know Server IP Address Previously.
>How Can I Get My IP Address ?
>Thanks..