Dial-up with LAN connection in XP Pro

My dial-up connection in XP Pro was working fine until I installed a LAN connection in my computer. I was planning to use the LAN connection to gain access to the Internet at the office and my dial-up connection for browsing at home.

I can connect to my ISP through my dial-up connection but I cannot browse the Internet. I tried disabling the use of a proxy server in my dial-up connection setting (Internet options) but this did not seem to help.

I hope someone can help me figure the correct configuration. Thanks