Cisco VPN / Firewall configuration

[G-Love]

All -

After much consternation, I was successfully able to install the Cisco 
3000 series VPN client on my FC2 box, with kernel 2.6.7  I had some 
problems connecting at first, but that was fixed with a simple addition 
to my iptables config file.  Here's my current problem (and seemingly my 
last hurdle to getting this to work as I need):

I'm connecting to the VPN server using NAT, as I have a firewall running 
on my machine.  I can get to all the internal websites with no problem; 
however, when I try to ssh to a machine on the internal network, it 
simply hangs.  When I try to ping the same machine, it times out with 
the following message:

PING: unknown host <hostname.myco.com>

Then I did a little experiement.  I got the IP address of the machine 
that I was attempting to connect to, re-established my VPN connection, 
then attempted to ssh to the machine using the IP address.  Lo and 
behold, it worked, and I was able to verify that I was, in fact, 
connected to the machine thru my VPN connection (the 3000 series VPN 
clients/concentrators allow for split tunnelling).

SO...it seems as thought name resolution does not work with the VPN 
connection enabled.  In fact, I can't see (ssh, ping,...) ANY machines 
while the VPN connection is active.  I tried pinging cnn.com, and that 
resulted in the same "unknown host..." message.  I'm a bit of a newbie 
to firewall configurations, etc, so any help on getting this to work 
would be appreciated.  I guess using the IP address is an OK workaround 
for now, but I'd rather not rely on this method.

Thanks.

            -greg