I assumed when I installed 4GB of ram PAE would kick in and I would see 4GB but top is showing me "3366428k total". I've never really dealt with PAE so I'm not sure what to do or if that is even my problem. I'm running 5rc11 with andECS - 945GZ/CT-M board and Intel® CoreTM2 Duo CPU E4500 chip.

The usual reason for a memory deficit from what was expected is memory reserved for onboard video.  The amount reserved in this instance looks a little odd, about 640MB.  Check your BIOS settings for the video, and see if you can drop it as low as possible.  UnRAID only uses text consoles, which use extremely little RAM.

Thanks RobJ! I will take a look at that. Good idea