hi shrigz
in our case we have a token ring And Giga bit based LAN and Mail and Intranet from leased lines from ISP's so we do have several gateways,but One router.
To access mails and Internet you can have OUTLOOK or maybe sendmail of Solaris,linux etc,these can be forwarded to a gateway with 2 NIC.One having your Internal IP and subnet ,and the other having the external or Fixed IP.YOu may have Win NT/2000 ,with MS Proxy running to serve you internet,mailing needs,or else you may have a linux box 7.4.2 ,and enable the firewaling and IP translation feature to save the same purpose with better security.