I'm in a similar situation. I have a 2.68 GPA with B.S Degree in Physics. I just graduated in May 2009. I took the General GRE and got 390 Verbal and 650 Quantative. I applied to grad school at Arizona State for their Nanoscience master's program. I was accepted provisionally as a non-degree student. The conditions were that if i took 3 classes, and maintained a "B" average, I would be fully admitted to the program. I was very excited to do this.
Almost all Grad schools require a 3.0 GPA and a 700 score on the Quantitative GRE. Mine is lower and I was lucky to get into that program even under provisional acceptance. Unfortunately, because of financial hardship I am not able to go to Arizona State for grad school.
Instead, I applied to a local school in Florida. The admissions director said this "To offset the problems in your GPA, and GRE, I HIGHLY recommend that you take the Physics GRE. If you get 50% on this, you have a very high chance of acceptance. We want you in the program, but we need to fight for you to get in, and we need evidence such as the Physics GRE score" I was disapointed that I was not going to grad school. And that I had to live with my mother for a while as I studied for yet another GRE. I looked at some of the Physics GRE problems, they are very tough. They are those nightmare physics problems that are in your undergrad physics textbooks that the teachers choose not to do because they are unnecessarily difficult. I was so angry!
Then I realized, that this was the right thing and best thing that could happen to my career as an upcoming scientist. How was I supposed to be successful in graduate school if i can't even get a decent GRE score and GPA? Studying for the Physics GRE would fill those knowledge-holes that were cause by slacking off in undergrad as well as those study skills.
I recommend that you study your ass off for the next Physics GRE, and show the admissions team that you slacked off in undergrad, but you are smart and ready for grad school. (That is...if you want to go to grad school in a scientific field..)
I hope this was some help,