I have an HTPC that has one slot space to accommodate a display card. I just ordered the Zotac 640GT (Keplar based) card. I've read that there are definite improvements in video decoding; which are features I can take advantage of. However, Im pretty sure my older card had much faster overall memory bandwidth (192bit verses 128bit); which kind of bums me out. I realize that memory bandwidth may not have much to do with HTPC playback; but, can't help but feel like I kind of took a step backwards in overall 3D performance.
Anyway, before ordering, but couldn't find any true single slot Nvidia based cards with 5th generation Purevideo that had faster memory bandwdith. As far as I know the Keplar based 640 GT 128bit memory bandwidth is as good as it gets for single slot space solutions.