DjArtifact :
I have 1 580 at the moment and I plan to add a second when I need to. Anyways I'm kind of set on water cooling and I want to buy one nice case for around $250 so I don't need to upgrade cases all of the time.
The GTX580 is still a very nice card, but it is being obsoleted by newer 28nm cards that run cooler with less power.
Evaluate the option of upgrading to a GTX670/GTX680, planning on sli later if "son of kepler" does not arrive near the end of the year.
Go ahead and buy a great case, but you really won't need liquid cooling with the new cards.