Can't say anything about surround sound headsets, but I own a pair of wireless headphones myself, and I have to say that they work really well. They are Sennheisers as well, and they are on the upper range of models. Can't remember the model name any more, as I bought them in like 2005 or something (might be the RS140), but they are still working just fine. There is no lag at all in the sound with them, and they have a range of 100 meters (300 feet) if there's no obstructions in the way. I've been outside mowing the lawn with them on with the transmitter playing music in my room, and it works quite well except for a few areas that have a dip in signal strength and the sound dies, so as long as you're inside your house you should be able to walk around freely listening to whatever you have them plugged in to. I did sometimes get interference though, such as being able to listen to the neighbour's TV or something if I held my head just right, but it was only within a tiiiny area, usually with a tilted head in an unnatural position.
EDIT: Of course, this is Sennheiser, which is one of the better headphone producers out there in my opinion. I'm sure there are wireless headphones out there that are complete garbage. When I bought these, there were even infrared wireless, which would cut off as soon as there's no visual between the headphones and the transmitter for example. Also, it's hard to trust consumer reviews sometimes, as people can't always tell garbage from quality. Then again, don't listen to hardcore audiophiles either, as they are usually the suckers that go for the $200 cables.
