Headphone does not work as sound device

Hi,

iMac 2,66 GHz with Parallels Desktop 4 and Windows XP SP3 using Dragon Naturally Speaking 10 Preferred (DNS).

My C-Media USB Headphone Set will not be recognized from DNS. How has it to be configured to make it work?
I have no problems with VMWare Fusion to work with the headphone, why this problem with Parallels?

My configuration:
Input: C-Media USB Headphone Set
Output:
C-Media USB Headphone Set - does not work
Standard und Built-in Output does not work either.

Connecting with USB as Hardware makes bothering noises in the headphone.

Who can help me. Otherwise I have to sell Parallels because I do not need it then.

regards

riconus