You can run the tool from the Administrative tools or from a command prompt: MdSched.exe. The other tool is Memory Diagnostics, which also runs in the background (if it discovers a problem, it runs diagnostic tests, which is added to the event logs), but you can kick start it if you think your system is having memory issues. This is a nice enhancement from earlier times where you had to start shutting down programs to conserve virtual memory but couldn't be sure which ones were the culprits. When it detects a shortage of virtual memory, it displays a warning and lists the highest-level offenders for you to shut down. That is to say, it basically keeps track of all your virtual memory on the system, so it can tell when your virtual memory is running low and also identifies which programs are using the most virtual memory. The first one is titled Resource Exhaustion Detection and Recovery (RADAR), runs completely in the background, and monitors the system-wide virtual memory commit limit. In fact, two tools are running in the background to address memory issues with Vista.
Microsoft used to make the memory diagnostics tool available as a separate download for those in the know, but now it's included in the Vista OS.
It's a fact of life that memory problems are hard to diagnose, and it's frustrating if you are the one dealing with them.
pdf of the 'System Recovery and Diagnostic Tricks' chapter here.
