You will need fairly good airflow through the case as it is passively cooled and even when I just started the PC with the lid off the case it seemed to get very hot very quickly.
I have had a problem with the card in MediaPortal. Stuttering occurs every second or two in live TV and playback of video after the PC has come out of hibernation. This may just be the Forceware drivers. I have managed to get round it at the moment by turning off hardware Acceleration in the PowerDVD Codec. This is not ideal, as part of the reason for getting the card was the hardware acceleration. Hopefully the problem will be resolved in the new Nvidia drivers due out in June 2007.