I (sometimes) use a USB handet with skype, because it is on my laptop it gets unplugged all the time i find this causes skype to loose its settings! (especially rebooting with it unplugged).

so every time i want to use it i go into skype into the options and select usb device in the audio settings (and i leave windows (control panel) set to my computers soundcard), this routes my computer audio thru the computer and skype thru the handset.

my voipcheap software accepts 2 lots of settings (ie usb and computer) and has a loudspeaker button to toggle between the two -very handy! (and it doesnt loos its settings, if the usb handset isnt plugged in when you reboot it simply uses the other!).