Internal audio cards, are they really good?

Now that most of us are using -or planning to use in the near future- audio files stored in our computers/servers, would like to know if at this point, there are really good options in the internal audio cards arena to be use it as DACs in our system. There are some that looks very interesting because can decode stereo files and 7.1 audio/movie files:
Onkyo Wavio (several)
HT omega claro
Asus xonar and more ....
what are your experiences in this area?, if chips are the same as the ones use it in external dacs, why can't be more/less the same?, is really computer noise an issue? can it be heard? .....