Hi Andy,
A soundcard with a hardware wavetable has build-in sampled sounds, whereas regular soundcards use synthesizers available in the OS (Windows f. ex.).
This technology is not very popular any longer, and one of the last brands offering it is Creative.
However, you don't need such a soundcard to use EarMaster (fortunately!), especially as we have added a latency compensation tool in the program in order to neutralize any delay for rhythm exercises.
So in conclusion, you should not worry about what soundcard is included in oyur new computer. Any internal soundcard will do, as the sounds will be generated by Windows'/OSX's built-in synth.

- Because in Music, We're All Ears... -