Q: Meet Requirements--why can't I upgrade?

Not sure what year I got my iMac (I think it was '08) but it crashed last year and I got a brand new system installed, so I'm not sure what that makes it now, and I can't find the documentation under About This Mac.

Don't mean to be daft, but where do I find that?

Sorry, just saw your reply. There is no model identifier that I can find under hardware.

Duh, yeah, I was looking at everything UNDER the hardware labwl.

  Model Name:          iMac

  Model Identifier:          iMac5,1

  Processor Name:          Intel Core 2 Duo

  Processor Speed:          2.16 GHz

  Number Of Processors:          1

  Total Number Of Cores:          2

  L2 Cache:          4 MB

  Memory:          4 GB

  Bus Speed:          667 MHz

  Boot ROM Version:          IM51.0090.B09

  SMC Version (system):          1.9f4

So I guess I'm NOT 7.1 or higher. Probably a dumb question, but could they have put in an older version when they rebuilt it?

Mine's white. I assume that's the polycarbonate. But as i understood it, they upgraded the motherboard in 2013 so that shouldn't have to do with the casing, should it?