There is a tool on codeplex that is well know about with the tech guys who analyze system performance issues but it’s a handy tool for using in pre-emptive monitoring when you are doing UAT, System testing etc for an implementation. You can find it here
Add it to your kit bag of tools as well as the trace parser that is in the product. As well for on-going monitoring the diagnostics service that is part of Lifecycle Service. As well if you want to use System Center for on-going monitoring with the MOM pack for Dynamics AX.