I, along with MANY others do listen to the 24/96 or 192 stuff. There are a couple of ways to do it.. take a digi-out of your soundcard from your computer into the DAC of your playback gear or burn a DVD-A, which requires DVD-A authoring software along with a dvd-a player. I'd say you'd be able to notice subtle differences on a "mid-fi" playback setup, but the more high end the system, the more dramatic the effects of higher bit depth and sample rate. On my playback gear there is ALOT of detail gained by a 96khz recording when compared to a 48khz.. The more bits.. ie. 24 compared to 16 bits seems to add depth to the soundstage when played back.. I've found my favorite HR media to be SACD, which is comparable to 20 bit / 2.2 Mhz..
About the computer specs.. anything above 500mhz and 196MB of ram should be more than enough (check your soundcard specs). But you will need much more than 10GB of HD space, expecially if you plan on running 24/192. I'd say a min of 30GB.