I thought a base 21 would be good enough for me but having owned my new iMac over a month now I can safely say I messed up. I use Parallels with Windows 7 and do photo editing in LightRoom 4. I was convinced this would be enough. Having spent the last month watching the beachball spin I have no problems saying I got the wrong machine. Almost everyday it gets stuck to the point of a hard reset. I took it into Apple and of course I could not replicate the problem. The Apple guy told me what I know that I probably need more RAM. I'll be selling this and getting a 27" with a Fusion drive and I'll probably max out the RAM. My lesson learned is that I am an idiot you should always get more than you need if you are not sure and can afford it. I'm thinking I will lose 200-300 by selling a 1 month old iMac? Anyone else feel my pain or make a similar mistake?