I will be deploying a ISA Server 2006 on my network soon. It will serve 40 users/clients to begin with, with potential increase to 100 users/clients. Its main purpose is to act as a Front End for Exchange 2003/2007. Exchange will be single machine, 64 bit, 4 GB DDR2-800 RAM initially supporting two external .com domains. LAN is Windows 2003 R2 native AD Domain, which ISA Server 2006 will be a part of.
I plan to use a 32 bit machine for ISA Server 2006. It has an AMD XP-2800 processor (256 L2 cache), 333 MHz FSB, 2 GB RAM, and Broadcom BCM95820 SSL Encryption Accelerator Cards. The network internally is GB Ethernet, and the Internet Connection is 10 Mbps DS3, which may be upgraded to full 45 Mbps as # of users increase.
This ISA Server will only perform Front-End Exchange duties initially, but may expand to Web proxy/app layer firewall as well. Will the hardware config described above be enough for current and future use or should I plan on deploying a 64-bit machine for ISA Server?
If there is a hardware HOW-TO guide based on # of users and bandwidth?