It turns out you don't need much magnification to see the motion of the spermatozoa (about 40X!). A local department store had a Christmas sale on a cheap microscope set (less than $20 US) so I had to get one. Even with the less-than-professiona equipment, the motion was very clear on a fresh sample. Now if I could just figure a way to patch in a camera - a New Years project, perhaps?
For those interested - here's a link to a youtube video (not mine) :http://www.youtube.com/watch?v=vvnEsOaKxuw