I wrote a little article for Complex on how to buy a fixed-gear bike. The majority of the tips apply to bike shopping in general. Incidentally none of the Fairdale bikes are fixed but you could throw a fixed cog on the other side of the hub if you were into that kind of thing. Check out the story here.
Oh yeah, you can still win the Riot bike from Karma Loop (which is a one of kind fixed Fairdale) here.