Join 2 Networks

Howdy,
I have a cisco 1720 router, windows 2003 PDC, 2 2950 cisco switches 1 cisco PIX.

Network1. The PDC acts as DHCP and has to authenticate all users and gives ip 192.168.0.x.

Network2. Has PIX 192.168.10.x with applications behind it.

I would like to join the 2 networks all clients on network 1 to communicate with network 2 without changing the current topology. I have tried vlans with no success.
Please assist