I have the sennheiser PC360 headset and have been extremely impressed with a good sound card. Much better than the Medusa 5.1 headset I had before. With a good sound card the virtual surround is great for gaming and also films and music. Loads of bass.
I personally tested the psyko 5.1's with an HT OMEGA CLARO Plus+ and was blown away, the surround sound was perfect and I could hear things that I couldn't with my GameComPro1's.. Not sure about the senns or logitech's, have not tested any of those. I don't really do wireless, I find it more of a hassle than anything.. I like my wires, assures me that I have the best connection possible.