"The Darwinian theory of evolution is no more nor less than the great cosmogenic myth of the twentieth century." - MICHAEL DENTON, Molecular Biologist

If the days of creation are really geologic ages of millions of years, then the gospel message is undermined at its foundation because it puts death, disease, thorns, and suffering before the Fall. The effort to define “days” as “geologic ages” results from an erroneous approach to Scripture—reinterpreting the Word of God on the basis of the fallible theories of sinful people.
It is a good exercise to read Genesis 1 and try to put aside outside influences that may cause you to have a predetermined idea of what the word “day” may mean. Just let the words of the passage speak to you.
Taking Genesis 1 in this way, at face value, without doubt it says that God created the universe, the earth, the sun, moon and stars, plants and animals, and the first two people within six ordinary (approximately 24-hour) days. Being really honest, you would have to admit that you could never get the idea of millions of years from reading this passage.
The majority of Christians (including many Christian leaders) in the Western world, however, do not insist that these days of creation were ordinary-length days, and many of them accept and teach, based on outside influences, that they must have been long periods of time—even millions or billions of years. (Ken Ham)
In a nut shell, if we believe that in millions of years BEFORE man evolved, we have a huge problem, because there would have been death, thorns and disease Before Adam and Eve. Do we trust the Bible or not. If we can't trust the Bible here then how do we trust it anywhere else? Yes we do have scientific studies that support God's plan. But no research or scientific discovery can ever prove one way or the other, so we must ultimately decide who we trust more. Fallible man or a Holy God. Just a thought :)
Check out Answers in Genesis They have lots of resources for lay people and academic research for the serious students.