A computer can belong to only one domain or one workgroup at a time. Are there DHCP servers in the office and at home? What are the IP addressing schemes in both networks?
You might want to utilize Windows XP's "Alternate Configuration" to make it easier to switch between your home and office networks, if one of those networks uses DHCP.
To configure TCP/IP for an alternate configuration:
1. Open Network Connections
2. Right-click the network connection that you want to configure, and then click Properties.
3. On the General tab (for a local area connection) or the Networking tab (for all other connections), click the Internet Protocol (TCP/IP) component, and then click Properties.
4. On the General tab, click Obtain an IP address automatically.
5. On the Alternate Configuration tab, click User configured and then type appropriate values for the following:
• IP address
• Subnet mask
• Default gateway
• Preferred and alternate DNS server
• Preferred and alternate WINS server
Also see:
http://www.windowsitpro.com/Article/ArticleID/27129/27129.html