W2K Pro / XP router between to network segments

How can I configure my W2K Pro / XP Pro machine to act as a router between to network segments?
Routing is configured on a W2K Server / Windows Server 2003 machine by use of the RRAS snap-in. However, this console is NOT available on a W2K Pro or XP Pro machine.
If you have 2 small network segments populated with no more than a handful of computers per segment, you CAN use a W2K Pro / XP Pro machine as a router between these segments.
First, you need to install at least 2 NICs on the machine.
Now you need to configure each NIC with the appropriate IP address for the segments that it's connected to.
Next, you need to configure that IP as the Default Gateway for all the computers on that NIC.
For example, if you have 2 segments (we'll call them Segment A and Segment B respectively) with the following Network IDs:
Segment A - 192.168.0.0/24
Segment B - 192.168.1.0/24
(/24 means 255.255.255.0 - see my What's CIDR? page for more info)
and on your computer you have 2 NICs (we'll call them NIC A and NIC B respectively) with the following IP addresses:
NIC A - 192.168.0.1
NIC B - 192.168.1.1
Then the IP addresses of NIC A and NIC B will be the Default Gateways for segment A and B respectively.
Next, you need to configure IP Routing between the segments. As I said, this feature is not configurable via any GUI in W2K Pro and XP Pro, so you'll need to edit the registry:
In the Run command type Regedit.exe and press Enter.
In the registry navigate to

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
                                                                
Select the "IPEnableRouter" entry (by default the value is 0) and change it's value to 1.
Close Regedit.
Reboot.