Database size is really the main issue to determine. Obviously if you go with standard, you'll need to limit mailbox size accordingly to avoid maxing out the database. I supported 200+ users on Exchange 5.5 standard for some years without many problems; you just have to keep the "power users" under control. It really comes down to how they use email; if they have a lot of heavy email users who send and receive a lot of attachments, enterprise version might make sense. Greg L. _____ From: Scott Vansingel [mailto:Scott_Vansingel@xxxxxxxxxx] Sent: Wednesday, April 27, 2005 9:35 AM To: [ExchangeList] Subject: [exchangelist] System Requirements http://www.MSExchange.org/ Group, I am trying to find information about the system requirements for Exchange 2003 if you have X amount of Users. We have a customer that would like a Exchange system for 160 users. I am not sure if Standard will work or if they will need the Enterprise edition. I am aware of the 16Gb store limit for standard edition. Just wondered if there is a formula for the different versions. Thanks