Parallel Programming

Hi everyone
I wanted to know if it is possible to run two functions in parallel rather than one after the other. I am actually fusing data from inertial sensors(which are very fast ) and GPS (which is very slow). So, when GPS is being read (using Serial Port), I want to be able to read my inertial sensors data (using I2C). Please give me any valuable suggestions.

Chandra

Sorry for the disturbance, I just realized that adding a Serial.available() for GPS reduces the read time to abt 2 ms. I checked it using millis() before and after the Serial.read(). It should not be a problem. Thanks anyways

Chandra