Analog to USB headset

Hello. I am looking into buying a new headset. The one I am looking at is USB, my current one is analog and goes directly to my sound card.

My sound card is integrated with my Gigabyte EP45-UD3P mobo. The sound card is:

http://www.realtek.com.tw/products [...] ProdID=173

The analog headset I currently have is:

http://www.plantronics.com/north_a [...] amecom-377

And I am planning to get:

http://www.logitech.com/index.cfm/ [...] 5&cl=us,en

So I was wondering, does the USB headset use my current sound card in any way? Will I notice a drop or improvement in sound quality if I switch to USB from analog (I've read that my sound card is very good for integrated, 192khz and supports 7.1 surround). I would love to have a headset that supports 7.1 rather than just stereo audio, however, I do not want a drop in sound quality. I am hardly concerned with the mic quality as I rarely use it.