I have a couple r9 290's coming in today and I've read somewhere that it would be ideal to uninstall all AMD drivers before putting in the new GPUs. Is this recommended? Anything else I should do before installing the new GPUs?
If you are switching from Nvidia to AMD then uninstall your old driver. If you are upgrading from an older AMD card to a newer card you shouldn't have to do a thing unless your old card was several generations old.
Have you accepted Raspberyl as your loli and savior?