So what's the oldest/cheapest system you can run it on? I'm planning to upgrade my PC for CivV (it's better than installing Windows on my Macbook Pro) but my budget is minimal. The current machine is ages old Pentium 4... and I have the feeling that that won't cut it.
I am able to run this game with a Pentium 4, which is well below minimum specs. I do have 4 mb ram, and an ATI in the 5000s. So that's about recommended.
Fwiw, I absolutely love the changes, the interface is much improved with one major exception. There is know direct understanding of enemy civs relations to you. Like in Civ 4, it would tell you "-4 you made an arrogant demand". That is gone and needs to be reintroduced imo.
It's all a little simplified, making choices more friendly for casuals, but the depth is there. Workers are still moronic when automated.