Tim
Thanks for the question. Server monitoring is a feature of our paid load testing tools. Currently SmartBear sells LoadComplete, which is soon to be rebranded as WebLoadUI Pro. Either of the paid versions (as well as loadUI Pro for API load testing) offer extensive server monitoring and charting (both real time and off-line) for server metrics.
You can visit
http://smartbear.com/products/qa-tools/load-testing for a trial of LoadComplete (which has the same interface just a different name, at present, as WebLoadUI), and loadui.org for a trial of loadUI Pro.
Wish you success in your load testing!