Features of VMM?

[Pejo]

We're looking for a method to inventory our virtual machines (all running on ESX 3.0 servers). The information we want to access easily is for example the virtual machines disk size, used disk space, RAM etc. Is VMM the solution for this? Will VMM make it possible for us to create reports with SIM that contains this information? Is it possible to manage this without using VMM (that is, doing this with the basic funcionality of SIM)? Buying VMM for moving, creating, backup etc virtual machines is not that interesting to us as we use VirtualCenter.

We're running SIM 5.0 today and want to know if there is any use in evaluating VMM.