Currently we have these servers :
Windows SBS 2003 premium on IBM X266 double Xeon F43, 2GB ram. DC, exchange (70 users), Mssql.
Windows 2003 R2 32bit on IBM x3400 with double XEON E5310 and 4GB ram. Terminal server (40+ users), ERP application based on uniPaaS platform from Magicsoftware, and Pervasive sql.
Ubuntu 8.04 (simple pc box) with squid proxy, GLPI system and PHPBB3 forum for internal use.
Recently number of concurrent users on Terminal server passed 40 users in rush hours and it gets stuck frequently. Therefore we need an upgrade. I think about transfer all physical servers to virtual servers based on cluster of 2 physical servers for reducing downtime. I think we will grow till 50-60 concurrent terminal users in rush hours. I also plan to virtualize 10-15 Win XP/7 workstation (office,ERP etc), and there is a little probability for Asterisk\Hylafax for 100 users (if it possible on same VM). Also we need NAS storage for 2-3TB.
What hardware upgrade/purchase we need for complete this task?
Which VM solution is preferable VmWare or Hyper-V?
What backup software should we choose? Acronis or something another?
Thank you in advance.