I have an XFX 8800GTX installed in my modded SD32G2 now!
(I had previously used this case mod with a 7800GTX 512 and recently an 8800GTS)
For the increased power demand of the 8800GTX, I added a Thermaltake Power Express 250W PSU in the optical bay. I used a PCI-E molex splitter from the Shuttle PSU and 1 PCI-E power connector from the Thermaltke PSU - efectively splitting the load between the two PSU’s.
The system runs extremely cool and is nearly silent, I have been gaming on it pretty hard and it has been 100% stable.
It was a bit tricky to get the card installed as there is practically no clearance in the front. I ended up removing the single slot PCI bracket from the rear of the card and setting it up in the rear chasis frame bracket (loose) and worked the card into it, then mounted it to the board afterwards.
The Shuttle is insanely fast and matches the performance of my 680i tower system now!