Gtx 570 and Civilization 5

So I installed my GTX 570 Graphics card, and was just trying games, I assumed I can max out just about any game now. I tried Crysis, and that was maxed, tried Fallout: New Vegas, that was maxed(not that it's a graphically intense game), and then I tried Civ 5. I couldn't turn up the leaders scenes past medium, but everything else I was. But the game won't start with everything turned up. I thought Crysis looked more impressive then Civ 5... So I don't know why this card can't max out Civ 5..

My specs are:

Windows xp

Quad Core Intel Q8400 2.66Ghz

Gtx 570 1280ram

4gb DDR2 Ram

Does Civ 5 use any DX10 or DX11 features? You're running Windows XP, which can't use anything beyond DX9, so that might explain it if so.

Yea I'm only running xp in 32 bit, and yes Civ 5 does use some directx10 and 11 feature, but it has both a option of running in 9 or 10 at start up.

I'm getting it for Christmas I'm pretty sure, but it was making me scratch my head why the 570 can't run Civ 5, my card before it was a 8800 gts 320mb and it ran it just fine (not maxed out though)