It's a great case..I even picked it out for my brother. But it's steel.
The XPS 630 case is aluminium and it's at least 3mm thick. Huge difference in acoustics and cooling. The 630 gets a great review for it's low temps and low noise. It's way quieter than the Antec 900 even with all the fans switched on low. Plus the two 3780's are better than the 9600GT. So for the price and the warranty I'd say the XPS is worth it.
Even my own system is way noisier than it but that's down the qx6700 which could fry an egg at idle temps.
It's all down the op at the end of the day..Not sure how the return service works with Hardwareversand.de but imagine it would be a balls returning a pc to them? Correct me if I'm wrong.