I know that USB headsets itself do work fine, but that's not what I'm looking for.
As stated before I'm thinking about an USB mike only - for sound output I'd still use my Audigy SE soundcard. My orginal question was wether such a
combination should work without trouble, and if USB mikes are really superior to conventional ones (clearer, louder signal)?
It seems that with both your mike and headset acting up through your soundcard, but not through your on-board sound, that the problem is likely in the mic connection to your soundcard. If you want to try the cheapest method first, go down to the local harware store, buy some electrical contact cleaner and spray some into the mic jack. If that doesn't work then it's probably the sound card.
Unfortunately both sound card's contatcs had been cleaned and still no joy.
I have to add that my mike problems are limited to AH only. Ever yother application I tried (teamspeak, skype, windows sound recorder) worked just fine.