I definitely do think that you have a shot at some of those schools (esp. UT Austin and CMU), but there are two main things that you'll need to do:
1. You're at the high end of the typical age range. Schools won't discriminate against you, but you'll need to be able to credibly answer the "Why an MBA now?" question.
2. You don't mention in your post, but you will also need to present a well-rounded application... That means more than having a good GMAT score and good work experience. What makes you an interesting person outside of your job? What community service have you done? What other interests do you have?
Don't worry about your GMAT and GPA as much as those issues that I mentioned above.
I'm not sure what you want to do post-MBA, but if you want to stay in IT, also consider schools like Maryland, Krannert, and maybe Vanderbilt.
Scott