I own the one in the middle, upgraded to 4GB of RAM. http://support.apple.com/kb/SP485 I'm looking at the base model, upgraded to 4GB of RAM. I'll probably upgrade to 8GB, but let's say 4GB to keep things fair. http://www.apple.com/macmini/specs.html Will I see a noticeable improvement in speed? With my iMac, I'm seeing the spinning wheel a lot more when moving in and out of programs/pages quickly. I don't do any heavy duty stuff. I use my computer for the internet, light editing in Aperture, and running my very large iTunes database through an external drive. I was planning on upgrading to an 27'' iMac but I'm realizing I'm spending a lot of money for power I don't really need, though the screen would be nice. But I could just get a different screen for a few hundred. I know it won't compare to the iMac, but I don't think I need it to. I also feel like it'll be a better value in the end if I decide to upgrade again in 3 to 4 years, seeing as I'll only lose a few hundred dollards compared to close to a grand. EDIT Now that I think about it, I could just use my current iMac the main display, saving me from buying a keyboard, mouse, speakers, and a monitor.. That's assuming my iMac CAN be used as a separate monitor.