SO, are you using multiple NICs or something? Anyway, to bridge without the wizard:
Open Network Connections
Select the connections you want to bridge, e.g. two ethernet cards, ethernet and hpna, whatever
Right click -- and choose bridge connections.
Does that sound like what you want?
In case you are interested and haven't seen it yet, here is an excerpt from the WinXP help about the logic behind bridging. In your case, you may be bridging multiple ethernet networks.
Using a mixed network environment. When planning your home or small office network, you might want to use a combination of Ethernet, wireless, and home phoneline network adapter (HPNA). For example, you might have two computers in adjoining rooms that are connected using Ethernet adapters and a network hub. If you have other computers in other areas of your home or small office, you can connect those computers to the network using a home phoneline network adapter (HPNA) or wireless network adapter.
In this example, there are two computers in adjoining rooms that are connected using Ethernet network adapters, cables, and a hub. One of these computers is running either Windows XP Home Edition or Windows XP Professional. There is a third computer in your child's bedroom, and a fourth computer in the den. The bedroom and den computers each have a home phoneline network adapter (HPNA) installed and are on a network together. To connect the two HPNA computers with the Ethernet computers, install a home phoneline network adapter (HPNA) in the Ethernet computer that is running Windows XP. If your laptop computer has a wireless network adapter, you can join it to the network as well by installing a wireless network adapter in one other computer on the network that is running Windows XP.
In a mixed network, also called a multi-segment network, one or more computers have multiple network adapters. Windows XP Professional and Windows XP Home Edition have network bridging, which allows the computers and devices on each of the network segments to communicate with each other. Without network bridging, the computers connected using Ethernet can only talk to each other, and the same for computers using HPNA or wireless. Network bridging makes each of these network segments transparent and appear as one continuous network.
By default, the Network Setup Wizard automatically creates a bridge when multiple network adapters are found on a Windows XP computer. The Network Setup Wizard does not bridge a network adapter that is connected to an external DSL or cable modem.