Can I port forward to a different subnet?

Can I port forward to a different subnet?

I have a Westell 327W DSL modem/wireless router.
I also have a Netgear WPN824 that I'm using as a wireless access
point. The 327W does DHCP and all the routing and port forwarding
on a single subnet 192.168.1.x
The WPN824 allows high speed access to 108Mbps devices
and solves the problem of more wireless cards than will
fit in the MAC filter table of the 327W.

Wireless is set up for WEP, because my favorite web-surfing
handheld can't do WPA.

What I'd like to do is give the WEP device access to the web,
but not the rest of my network. And I want the wpa on the
netgear high-speed wireless.

I moved the wire to the main computer from the 327W to the netgear
lan port and hooked the netgear WAN port to the 327W. I turned on the
netgear DHCP server and swtiched it to WPA. Netgear subnet is now
192.168.100.x. Now, my handheld
device can talk to the web, but can't see the main network on its
different subnet. Everybody can talk to the web. I have myself
convinced that I have better security...???

But, I have a problem. I need ports forwarded thru the 327w to to the main
computer on the second subnet managed by the netgear router.
I have no idea how to do this.

The 327w manual talks about public lan and private lan??
Can I just DMZ everything to the netgear and use its firewall
and filters?
I thought about trial and error, but there are a lot of options
and I don't even know how to tell if port forwarding is working
without having someone on the other end of the web to help.
Is there a diagnostic tool I can use??

Googling suggests that I'm not the only person with this problem,
but no answers were presented.

So, I need to understand how to port forward thru two routers
of come up with a different way of doing this.
Would be much easier if I could use WEP on the netgear, but that
doesn't do what I need done.

Suggestions?
Thanks, mike