If you can take the cassette off, you can figure it out. One, because then you could see the freehub body (and Campy and Shimano are quite different) but to do this you'd need the correct lockring too, so you'd already have figured it out by using a Campy or Shimano lockring. Although I guess it's possible that the Ritchey wheel could use a Campy cassette, with a Shimano-style lockring for ease of compatibility. And the lockrings are very similar, with the same number of splines, anyway.
Anyway, if you succeed in getting the lockring off (you'd need a chainwhip, too) and can look at the cassette body, you can figure it out; Campy splines are taller than Shimano, and a sort of V-shape ostensibly to better hold the sprockets tight. Here's a picture of a Campy...
It's also possible that you could tell from the spacing of the cogs, but I'm no expert on this.
Last edited by TallRider; 01-06-06 at 10:10 AM.