I just installed mandrake 9.0 on my PC. I have a
Linksys-BESFR41 router/switch, running DHCP. I have a 2 windows machines on the network....and they're fine. They obtain IP's no prob...

The linux machine boots up, but cant find a DHCP client?

Ive gone into the terminal, shut down eth0, changed config, brought eth0 back up, and restarted network services....

Ive also gone into the mandrake control center, to check the config. Ive run through the wizard....and re-configure the interface for DHCP, and to boot up with DHCP...

Ive also tried changing the gateway to the default
192.168.1.1....and that doesnt work. But if I ping my local loopback,,,I get replies.

What am I doing wrong?

make sure the physical connectivity is okay:

verify lights
ping the router
make sure the NIC drivers are installed properly
try connecting PC to PC and see if you are able to connect to the other PC

You could try manually configuring the ethernet interfaces

Have you tried running dhcpcd manually to see if it picks up an IP ?

HTH