Skype audio issues

Is anyone using Skype successfully with external soundcards? I've been speeding up moving wholesale to the Mac recently and have started to use Skype on the Mac. It's not very smooth sailing as no audio IO seems to take place for the selected devices in Skype when you plug in external soundcards. So for example if you set the external card for playback and the built-in mic for record, neither seems to work in Skype.

 

I've set the output to my soundcard, and the input to the internal Mic. Neither works when set up this way. I'll find a Mic to hook up to the soundcard and see how that works.

 

OK, so that's fixed. The other problem is that the person at the other end gets an echo of their voice along with mine. I presume this is due to the Mic picking up the sound from the speaker. How do I avoid this without going to a headset?