If you want to maybe do SLI you must get a full tower. Maybe a Coolermaster Stacker 830 or a Thermaltake Armor series. I hear great things about both of those cases.
For PSU just go to tomswiki and make sure you get a tier1 or 2. I am guessing around 700W of solid power will be enough if you decide to SLI in the future.http://www.tomswiki.com/page/Tiered+PSU+Listings
As far as cooling goes just make sure you get a nice case. Then max out as many fans in it as you can. Also make sure you have good airflow and no dead space. EX: Fans in front of case are pulling air in from the outside. While the fans in the back of case are pushing out the back of the case.