A Wave system consists of two parts – the “VAM” (Vertical Application Module – the part of Wave you see during administration), and the “ISC” (Integrated Services Card, which you do not see).  The VAM / Windows side of Wave is simply hosting Wave’s database, the user interface for administration, storing your voice mails, call recordings, etc.  Wave runs on a special edition of Windows Server referred to as “Telecom Appliance Edition”, where you would not run your typical server-specific services such as a domain controller, file server, Exchange server, accounting server, etc.  It is only running services required by Wave.  Wave’s voice resources and voice processing happen on the ISC and are not putting significant load on the Windows side of Wave.  Some of our largest single-system Wave deployments (500 users on a single system) are still running without issue on a previous generation IP2500 with only 2GB of RAM.