Home theatre: all the reviews I have read say that the Creative X-Fi is best, it actually up-mixes to 5.1 192kHz from stereo. It is very good for headphones, especially, making normal stereo sets ACCURATE 5.1 (3D soundscape object placement).
It's expensive, though, and not many games are written with OpenAL extensions (yet) and take advantage of the 130 voice capability (Battlefield 2 being one notable exeception), so the X-RAM seems a bit uneconomic. You do get a remote control and a 5