Several variables need to be taken into consideration when comparing GPA and GMAT.
For the GPA:
(1) Which school did the undergrad work take place at?
(2) What was the major course of study?
(3) Is there a rising trend, especially towards the last two years in upper division classes?
(4) Worked your way through school or bank-rolled by uncle buck?
For GMAT:
(1) Q/V are equally split?
(2) Numbers of times the test was taken?
(3) Rising scores with each retake?
(4) Cancelled scores?
Whereas the GMAT is definately the universal equalizer among business candidates from all different types of backgrounds, GPA shows sustained persistance in an institutional enviornment.
There are thousands of stories of people out there who have gotten into top programs with either a subpar GMAT or GPA, but definately not both. If you have a low GPA, mitigate it by aceing four or five university courses and make a special note of how you have changed or matured since undergrad in the optional essay.