Does anyone have any experience with installing and running at less than 300MHz as recommended?

I've got a 233Mhz which I can overclock, but I'd rather not if you know what I mean...

I honestly don't know if it will run at all - I can safely predict that you'd have to limit yourself to small maps, few civs, and animations turned off - just to get something playable. Even leaving the graphics to one side, the AI chews up a lot of CPU especially as the game progresses.

It also depends a lot on available memory (I'd say minimum 256Mb but more is better) and the quality of your graphics card - I run a 32MB Geforce2 which is nothing special these days. I'm assuming that your 266MHz PC may be lacking in these areas too?

Unless anyone else has a more optimistic view, I wouldn't recommend buying it to run on your PC (I'm assuming you haven't bought it yet?).