No real experience with these, but I did note the recommendation in at least one of Mickey's KB articles on speech recognition software that the USB mics are much less susceptable to hums and buzzes. The USB type reportedly convert to digital in the microphone so that all the power supply and monitor hums and buzzes don't get picked up on the way to the machinery (at least that's what they said).

It shouldn't make a lot of difference if you get a reasonably good quality mic and a good (shielded) plug-in cord.

You might be able to reroute the cord, and/or maybe replace with a better shielded cord, to get rid of some of the buzz with the one you have?

John