Two serial connections, one arduino?

I have two chips that I want to interface with one Arduino. The connections are serial for each. Before investing in arduino, how would I connect these guys to the 2009 board? Can i just assign any of the 14 pins or are there rules I have to follow?

The bit banging has been done for you with the software serial library http://www.arduino.cc/en/Tutorial/SoftwareSerial

The SoftwareSerial library has been superseded by the NewSoftSerial library, which corrected a number of deficiencies in the SoftwareSerial library. http://arduiniana.org/libraries/NewSoftSerial/

You may find the following useful... it talks about using SoftwareSerial. What it says also applies to NewSoftSerial, which you should use. (The tutorial just happens to predate my familiarity with the latter.)

http://sheepdogguides.com/arduino/FA1serial.htm