Cacheman can take over memory control from Windows to ensure optimal performance and ram usage.
You can define which applications have the most importance to you. When your system runs out of RAM Cacheman will take it away from non essential programs and give it to the important ones.
Select a process from the list and assign importance in the combobox.
You can also limit the maximum RAM a process can get. This can be useful for application that are constantly loosing (leaking) memory, but you want to use them anyway. A memory leak will probably result in slow system performance and instability.