Preparing for graduate school

[mbalthrop]

Hello,
I am new to this forum and would like to express my thanks to you all for providing such a helpful community. I have been reading through the various forums and have found so many useful discussions.

I have a question regarding ones performance in high school, and how that might affect ones chance at being accepted to their university of choice. A short background detail on myself will clarify my inquiry.

I did not have any idea what I wanted to do in high school, and I was also not an outstanding student. I graduated with a 2.9 GPA and scored a 25 on the ACT. I went into the military and began working towards my undergraduate degree in computer science.
Roughly a year ago I decided that I would like to study physics instead. This came about primarly as a result of studying mathematics and writing programs to solve mathematical problems. I began self-studying calculus, my text relying heavily on physical problems to introduce the student to the concepts. So I am now getting out of the military and applying as a transfer student with a 3.4 GPA (not great I know) to study physics. I know I do not have near the requirements to apply to the universities I desire (MIT, Cornell, Princeton, Caltech).

I am wondering how much my poor prior academic record will affect my chances at being accepted to the aforementioned universities for graduate school? This question is taking into account a dramatically improved academic record during my undergraduate studies, which is of the utmost priority to me. Regardless of whether I stand a chance at being accepted to the aforementioned universities, my short term goal is graduate school. Could doing very well in my undergraduate studies and participating in research make up for doing poorly when I was younger?

Please excuse the long post, thank you all for your time and any advice you can lend.

[TheBeast]

Your high school record is irrelevant. I don't think I've come across a grad school application that asked about high school performance. Concentrate on doing well in your undergrad program, study for the PGRE and get some research experience.

[mbalthrop]

TheBeast,
Thank you for your response, I was not sure if secondary school records played any role in the graduate school acceptance criteria. Thank you for your time, I greatly appreciate it.