Is this for gaming or do you just want good sound quality?
I would avoid the Audigy2, it resamples all the sound, and I am not sure about the audigy 4. If you need a gaming card get an x-fi, you can get one pretty cheap here:
it does not resample the sound, it supports bit matched playback, and ASIO 2.0. So if you were ever to add an external DAC, it would not be a resampled signal.