Anyone have a recommendation for what to upgrade/replace/add in
the following situation?

I just powered up a cable modem in the house, so I'll be dropping
the 28.8Kbps modem connection real soon.  So I'll need a NAT system
with Ethernet instead of my pc532 with it's pair of reasonably high
speed (for what they are) serial ports.  My hardware is as follows:

1   SparcStation LX: mainly used as an X server and console for the
    pc532, although it does have enough disk to build -current
    snapshots if necessary.
2   PC532: used as proxy system for the LX and the Macs my wife and
    daughter use.
3   233Mhz Beige G3 Mac: mostly runs Netscape, and Apps for the wife.
4   Mac 6100/66AV: mostly runs apps for the 4 year old.

Connections are:
A   10baseT Ethernet connects the Macs and the LX
B   pc532 Serial console on ttya of LX
C   PPP link from ttyb of LX to pc532
D   Modem on pc532 to ISP

Thoughts for cable upgrade:
I   Leave everything as is, just plug cable modem into the hub and
    have the LX do NAT/proxy service.
II  Get an SBUS le1 for the LX, move it into the linen closet with
    the cable modem.  Find new xterm.
III Get pair of Cabletron SCSI-Ethernet boxes and keep all machines
    in their current roles.
IV  Get new machine to do NAT use the SMC EZ Card 10/100 that the cable
    installer left behind because I did almost all his work for him.

Notes:

I like the idea of using the pc532 for NAT.  It may be "security
though obscurity", but I figure any script kiddie will just get a
core file on it rather than a root shell unless he really does his
homework.  The down side to this is that those cabletron boxes run
about $200 apiece when you can even find them.

The LX would be a real good choice, since it could fit in the closet
beside the cable modem.  It's small and doesn't generate too much
heat, but then I need a new X server/serial console machine.

Also, does the cable modem broadcast all my 10baseT traffic to the
neighborhood, or just the traffic between my single provided IPv4
address and their router?  If the former, I think I'd like a full
firewall to hide the local traffic...  (I guess a switched Ethernet
hub could do the job, but I suspect my 5 port $20 hub isn't up to
that task.) I could spend a few hundred on this, but I'd rather
keep the costs as low as possible right now.

Comments, Opinions, or Suggestions?

Jon Buller