I don't have a Vista machine here, but you should be able to open a command window (cmd) from the Start-Search window, type: ipconfig
Then press "Enter".
If you type: ipconfig /all , then press "Enter", you'll get a whole bunch more information than in XP.. too much for me.. Still, I believe "ipconfig" should get you what you want.
Hope this helps.
How do I find a PC's ip address in Vista?