I'm mainly using the machine for gaming, video processing and light video editing. I had to change out the Sapphire Radeon 6950 2gb that I'd been planning for last minute as stocks of the variety of the card that would fit in my case had run out. So I ended up going for the MSI TwinFrozr III OC/PE Geforce 560 Ti. I've been pretty happy with the build, though the weak spots are the existing slow SATA HDD, monitor, and keyboard and mouse which I've recycled from other computers. I've been able to run everything I've thrown at it with a smooth framerate on ultra settings and 1080p resolution. One notable exception is Flight Simulator X which is terribly optimized and requires some tweaking to get good performance on max settings.
The Storm Scout case is pretty great with one notable exception, it cannot fit Video Cards larger than 10.6", which can limit your choice of high end cards rather significantly.