Richard,

    You can only have one "default" gateway, also know
as "route of last resort".  To accomplish what you want,
you must set up a static network route for each subnet,
not a default route.  You also may need to set a route
to any subnets that attach to the subnets attached to
the NICs in the H70.  The interface for these routes
will be the NIC attached to the proper subnet.

Here's and example:

en0:  192.168.0.1
en1:  192.168.1.1

Route Tree:
route          destination        interface
-------------------------------------------
default        192.168.0.2        en0
default        192.168.0.2        en0
192.168.0      192.168.0.2        en0
192.168.1      192.168.1.2        en1

In this example, the default route goes to a device
on the 192.168.0 network.  This would be because that
network connects to the rest of the world (eg. the internet).

HTH

--David Nash
  Systems Administrator
  Systems Administrator
  The GSI Group