I've got a mid 2012 Mac Air that I enjoy using for most things, but the small screen just isn't cutting it for work. I run a small internet business from home and mainly need this computer to act as a shipping and tax station. Most of my packages ship online with usps.com and my taxes are done with quickbooks software. My vision is good but a 24" or 27" screen would make things much easier/faster. Few things I'm in a pickle about. Having gotten used to the fast speed of an SSD HD do I get an older '09-'11 Core Duo imac with a bigger 24"-27" screen or possibly get a mid '11 that has the i5 sandy bridge chipset, more expandable ram and bigger hd? From what I can tell the '11 are not expandable in the HD dept? My gut tells me an older imac with an SSD HD would be a more productive machine. Found quite a few imacs locally. Never considered buying a used computer but all my macs have been near bullet proof over the years. Budget is around $300-500. Appreciate any insight you guys can offer.