Sennheiser PC 360 headset

Hi everyone, my first post here  

I'm considering buying a Sennheiser PC 360 headset. Its really expensive though, and when I noticed it had two 3.5mm connectors instead of USB, I got worried. My speakers are connected in my (only) two 3.5mm sound card jacks, and I don't want to have to physically pull-out/plug-in the connectors every time I want to switch between the speakers and the headset - i.e. I want my headphones to go via USB so I can just go to Sound and switch with a click.

So the question is: does anyone know whether the Sennheiser PC 360 model headset comes with a USB adapter that lets you plug it in via USB? Some other (cheaper!) Sennheiser models definitely do. If not, can the thing be somehow plugged-in via USB anyway? Finally, is using a USB adapter to plug the headset via a USB port somehow detrimental to the sound quality?

Also, does Sennheiser PC 360 have an integrated sound card like the Logitech G35 and the Razer Megalodon?