The PC Sales Guide/Configurator (available for free from http://www.pscfg/downloads.htm
) has a Needs Assist function, whereby you can specify a series of Feeds & Speeds requirements, and it will find all the matching machines, both current and withdrawn in the past 2 years. If you need a machine that can get to 16 GB, you can specify that, separately from how ever much memory it starts with.
I tried to include a screen capture but that did not work, so any suggestion would be appreciated. Or, you can just get a copy of the tool and try it yourself.