soma lockrings have a little "extended thread tab", which may or may not fit all the way on your hub.

I got a milwaukee lockring (ben's cycle) for $8 plus shipping, for my no name track hubs, and the milwaukee ring fits better than the original (which was made from old kleenex or something)

for a fixed gear tire choice, you just don't want anything super light, get tires with a nice thick tread portion, and as everybody said above, michelin makes so many tires, you'll just have to shop around.