wireless networking problem

[Darr]

In this case, you don't *have* to use the WAN/Internet port on the DIR-615 
at all.

In the D-Link's web menu, SETUP on the top, NETWORK SETTINGS
on the left, the ROUTER SETTINGS section in the middle...
Set the Router IP Address to an unused IP in the same network of
your LAN. Check the Enable DNS Relay box. Click "Save Settings"...
After it reboots you'll need to reconnect to the DIR-615 at the IP
address you just set (instead of the default 192.168.0.1).
To access the DIR-615's setup menus and to set the scope of its
DHCP server are the only reasons for that IP address... other than
that, the 4 LAN ports on the DIR-615 amount to just a 'dumb' switch.

Set a range on the DIR-615's DHCP server in the DHCP SERVER
SETTINGS section that does not include the current static addresses on
your LAN. You can set the range to allow only 1 address if you'll only
ever want to connect 1 device (i.e. your netbook), but I'd allow room
for a few if you might have visitors with a WiFi device. Your decision.

Click "Save Settings" again.

Finally, connect one of the DIR-615's LAN ports (instead of the
WAN/Internet port) to a LAN port on the "LAN gateway" router.

You should be able to use the DIR-615 as an access point now, without any 
NAT'ing required.