[SunHELP] Configuration advice...

[Marvin Cummings]

Wondering if I can solicit some advice from the list on a setup I'm
thinking about implementing? My network is currently configured as
follows:
BellSouth DSL service
Linksys 4-port DSL router
Windows 2003 Active Directory w/AD an Integrated DNS zone
ISA 2000 firewall server
Windows 2003 web server 
Exchange 2003 mail server
I have a Solaris Ultra Sparc 10 workstation and an intel box that I'd
like to also install Solaris 8 on.
The plan is to install and configure sendmail on one of these solaris
systems and place it in front of my exchange server. This would allow
me to remove the linksys router and possibly use Solaris as my sole
firewall/router and sendmail as a relay for my exchange server.
What I'd like to know is what others may think of using Solaris as a
firewall/router with a DSL connection? I'm sure it can be used for
other things but I'd like to know how effective it is as a router?
Right now I have the ISA server acting as a firewall with the linksys
in front of it. I'm not too happy about this configuration but can't
afford a hardware firewall solution.
If anyone has any documentation on configuring Solaris 8 as a
firewall/router and sendamil on Solaris 8 as a relay for Exchange I'd
really appreciate it. I'm using the Mastering Solaris 8 book published
by Sybex to gather some solid info on this but welcomes any responses
or direction.

TIA