I agree with tkkoh. I have a BBA and MBA from a second tier Canadian research university and 3 years ago received offers from 2 very good schools; those would definitely be considered "top schools" if that term is defined as the top 15-20 schools in my discipline (accounting).
In my entering class, there were people from places like U. of Oklahoma, U. of Cincinnati, and so on. You have to keep in mind that people screening applicants get tons of qualified applications from international students whose schools they've never heard of, so they can't make offers primarily based on _where_ applicants did their coursework. In my mind (and theirs hopefully), _what_ they did is much more important, and if you've done well in civil engineering and economics, having gotten those degrees from a state school definitely won't be a big weakness.
University of Oklahoma definitely contains some extremely bright people
I went to HS in Oklahoma and many of the smartest people from my class attended OU.
If you plan on doing a grad degree anyways - and know to take advantage of opportunities at OU - its hard to turn down a free ride from OU + extra cash (they let you keep your other scholarships, usually amounting to ~$5,000 a year => $20,000 in your pocket right out of school).