Next upgrade?

Hey forum! I currently have a build with:
HAF 932
Blu-ray Read/write
i7 920 @4ghz
xfx 5870 (900mhz core, 1300mhz mem)
evga x58 sli le
6gb corsair dominator 1600mhz
2x 500gb 7200rpm HDDs in raid 0
1000W corsair PSU

So my question is what should be my next upgrade?
5970 ($700 on newegg)
or
rampage III extreme ($285 on newegg)
or
i7 980x (i can get it for $700)
or
(after mobo upgrade) gskill 2200mhz 8gb ($340)
or
mod my case and install a water-cooling (aprox $400-600 depending on what I water-cool [like the GPU and adding another radiator])

and yes I have read ALLLL about water-cooling so please... no one say that I have to read up on water-cooling.

thanks guys!

I'd go with Water Cooling and a second 5870 like Timop said. Or how about a solid state drive? They're a little expensive, but so is your rig, so I'm sure you could afford it. Massive performance benefits to be had there.

I think the best single upgrade for your system is an ssd. Great performance boost.

then you might go graphics upgrade/crossfire and/or water cooling further down the track

SSD for the games you play most.
Otherwise there is little to do, well you can do all sorts but aside from spending money and whatever fun you get from tinkering with your machine, you will get no real benefits, aside from an SSD anything you spend will be money for nothing in terms of performance as there should be nothing you can't play at high settings with that rig