Setup (bothway) NAT on NT 4.0 Server

Hi,
I need to setup a test environment with one NAT device (a Microsoft NT 4.0 or 2K Server) running NAT services with two lan cards. To these cards I will connect two PCs (using cross cables) & from both these PCs I should be able to ping each other. Here is the network for better clarity –
PC1 (192.168.101.2) <--> NAT Server LanCard1 (192.168.101.1) NAT <--> NAT Server LanCard2 (192.168.102.1) <--> PC2 (192.168.102.2).

Ping from PC1 should goto PC2 & visa versa.

Whats the way to implement this using NT 4.0 & Win2K ?
I have already tried it on Win2003 but it supports NAT only one way.. ie I can ping from PC1 to PC2 but not from PC2 to PC1. No firewall or port blocked.
Please help !

Akash