Paul, could you post asa config. For your inside hosts to go out internet you need couple of statement in your firewall.
e.g.
nat (inside) 1 0.0.0.0 0.0.0.0
global (outside) 1 interface
this should allow your inside get outbound access to internet.
as for your new IP block, make sure RDP is enable on the machine and that no firewall is neither enable if it is an XP machine.
access list should be something like this:
e.g
your static NAT is ok.
access-list outside_access_in permit tcp any host 72.164.x.x eq 3389
access-group outside_access_in in interface outside
HTH
Jorge
Jorge Rodriguez