A couple thoughts:
First, taking the Bible literally requires a belief that man has been on this planet for only 6,000 or so years. One poster advanced the theory that whole generations were left out of the Bible. If so, how do you explain Matthew 1 (genealogy of Jesus back to Abraham) and Luke 3 (genealogy all the way back to Adam)? Setting aside the fact that these two genealogies contradict each other--if there are generations missing in the Bible, then that proves that the Bible is inaccurate which calls the Christian God (alleged "author" of the Bible--2 Tim. 3:16) into question.
Second, there were undoubtedly large local floods in ancient Mesopotamia. But the problem is that the Bible describes a global flood. Genesis 7:19says "all the high mountains under the entire heavens were covered." (NIV). It would take some linguistic gymnastics to read that passage and argue that it's not describing a global flood. Sure, some people do this--but I think they're disregarding the plain language of the Bible.