I use to ride bmx, but gave it up to focus on school. In the process I've also become SUPER lazy.

I'm looking into buying a single speed or fixed gear bike just to stay active. I'm not necessarily looking for top of the line, I just want something reliable to ride around town, bike paths, etc to try to get back in shape/stay active. And I want to stay under $400 preferably. Only thing is, I know virtually nothing about them as far as makes/models go.

I've heard good things about Mercier and Windsor, but that's about it.

First off, I like both of these. Any feedback/opinions on these would be appreciated.

http://www.bikesdirect.com/products/..._al_carb_x.htm

http://bikesdirect.com/products/mercier/kilott_pro.htm

I'm leaning towards the Dawes SST since it's a bit cheaper and says something about the wheel being flippable to ride in either single speed or fixed gear?

Also, any other recommendations are welcomed.

And lastly, for someone looking to ride regularly to get back in shape and stay active, will it make a whole lot of a difference if I go with single speed or fixed gear? I understand fixed gears don't coast, but wasn't sure if that'd be much more beneficial as far as fitness goes.