I would try to launch a tcpdump/wireshark session on centos server to see whether there's dhcp traffic on it. Alternatively, when in static configuration, to see whether the icmp packets reach for NAT server (my feeling is they are not).
AFAIK, there is no limitation (or there should be none) on the 2k3 server. But of course, I could be wrong.
As a side note: I assume you also set the default gateway (as your nat server) and/or default route (through it) when in static configuration, not only the static ip.
=================================================
I will follow the good side right to the fire, but not into it if I can help it. -- Michel Eyquem de Montaigne