This is my Q700/SDSL Setup, maybe it will help.

     
	DSL Modem
		|
		|
          sn0 ae0-----Hub--Mac
		Q700      	  |
	                 Mac

Note: All computers are plugged into the hub's regular ports, not the
uplink port.

ifconfig.sn0:

inet XXX.XXX.XXX.XXX netmask 255.255.255.0

(where XXX is my static ip address from DSL provider)

ifconfig.ae0:

inet 192.168.0.3 netmask 255.255.255.0

resolv.conf:

domain dsldomail.net
nameserver XXX.XXX.XXX.XXX
nameserver XXX.XXX.XXX.XXX
lookup bind file

ipnat.conf:

map sn0 192.168.0.0/24 -> XXX.XXX.XXX.XXX/32 portmap tcp/udp 10000:40000

(where XXX is my static ip address from DSL provider)

ipf.conf was blank to start with and then I started adding filtering
rules. You can just leave it blank pass all packets but I believe there
file does need to be in /etc.

All the computers on the network have 192.168.0.0 ip adresses, use
192.168.0.3 as their gateway address and my provider's real DNS server addresses.

Do you have a crossover cable as one of your cables? Could that be the
reason you need to connect to your hub's uplink port?

cheers, 

Matthew Reilly