VPN Connected, How to browse files? Windows Vista

I am trying to establish a VPN connection to a server in my office from my laptop at home. I tried some of the steps as mentioned here:

• Connect to a network
• Connect to a workplace
• Use my Internet Connection (VPN)
• Then type server IP address and then my username & password.

After creating a VPN connection, I can see I am connected to it. Now I want to browse files on the server. But I have no clue where I should look for them.

I was thinking more of a simple step, like, Windows Run > Type ip address > \\124.345.678.900, then a prompt asking username and password, and finally a window opens to view the files.

I tried to google it, but still unable to view files.

Please help.

Update:
I didn't mention that when I try to connect to server via \\124.345.678.900 I get 0x80070043 error message.

1. How have you confirmed connectivity to your office network?
   Can you ping to one of the internal IP addresses that you know?
   • Were you able to do a domain login into your office network?
     Typically a network-share is not allowed without domain-login.
   • Do you know that the server-of-interest is allowed access over VPN?
     Sometimes VPN access is differently access-controlled compared to the internal network.

Update after comments.

• Yes, the internal IP addresses are usually 192.168.x.y
• Your comments suggest VPN connectivity is ok and you are allowed access too
• Since you can connect from another machine similarly,
  • What is the difference in this machine? (Is the other machine not Vista, for example?)

Update after new comments. Google lookup on the error gives,

• Unable to connect to server...error code 0x80070043
• Microsoft KB932920