IPSec and MN-500

I am trying to use my Sonic Wall VPN client on my WinXP
Llaptop. The router has been set up and upgraded to the
latest firmware. When I try to connect the VPN the client
shows as connected but the router log shows as the far
end trying to connect on TCP port 500 and being blocked.
The src address is correct. I tried to forward the port
using both persistant and application triggered port
forwarding but it still blocks the src IP. There may be
other ports needed but it won't continue until i get the
first port to forward. Is there some other voodoo that I
need to do?

When I open the DMZ to my laptop the client comes up fine
and I can ping an internal IP at the remote end. I would
like to avoid using the DMZ to connect to the shop.

Thanks in advance.

Mike