I am interested in owning a fixed gear bicycle, and I want to know what dimensions of the frame I should get. I am about 5 feet 3 inches, and my inseam is approximately 30 inches. Should it be around a 49 cm or 52 cm?

Also, since I just want an entry-level bike, I would like some opinions as well. Do these bikes make decent ones for flat-land riding?
http://www.bikesdirect.com/products/trackbikes.htm

Or, should I go to with something like this?
http://www.performancebike.com/shop/Profile.cfm?SKU=26545&item=30-1501&slitrk=schamp&slisearch=true

I know for a fact that the Mongoose is only a one piece crank, which I think is not as good.

Thank you in advance!