I was exactly in the same situation as yours 1 month ago. I decided then to build my home network: 1 firewall/router and 1 client.
I used Redhat 9 but Mandrake is very similar. You should split the
problem in 2 stages:
1) configure your local network
2) configure the firewall.
1) It looks like your 2 local network cards ( 192.168.0.1 on the server and 192.168.0.10 on the workstation ) are fine.
If you want to ping , be sure to desable the firewall that comes with Mandrake installation on both systems because some firewall could make the system you are trying to ping invisible ( rejecting ICMP packets )
Do a ping "by IP adress" like ping 192.168.0.10
After that you'll have to configure the /etc/hosts files to match the names you'll give to the systems with their IP adresses.
2) For the router/firewall, I uses the Firestarter program ( you can use Turtlefirewall, but it requires the Webmin application )
Of course, reading the Linux network administrator guide and the the linux networking howto wouldn't hurt