Thanks Laura! I went to the LBS yesterday and had the guy explain it to me too in very small words with lots of drawings and his own fixie. After fiddling around with the cog at home, I realized it may be a "flip flop" hub but it's not got a built in freewheel. But you are right, it's a cheap part, so no biggy. Went ahead and ordered all the other stuff I needed too while I was at it. Hopefully I can get this thing together soon enough!

Thanks a million