Why I am getting two IP addresses when I connect to my work through VPN

Guys:

I have laptop at home, connect to my home router using WLAN, I do get
IP address from my router 192.168.0.2, I used to connect to my work
using VPN, when I do "ipconfig" I can see two IP address, one for
local LAN and other for VPN, why two IP addresses?.

Also when I work using VPN, I can't go to any of the web sites, like
www.yahoo.com, when I disconnect VPN, everything is OK, what was the
reason?.

Thanks.