I've read most of the posts here, and I'd like to propose a different side of the problem of Genesis that perhaps some of you haven't considered. It goes like this:
The days of the week have had names as far back as can be traced, some trace the names back to the ancient Sumerians. The Sumerians worshipped the Sun, the Moon, and the planets. From what I understand, there are five planets that they knew of that are visible without a telescope: Mercury, Venus, Mars, Jupiter, and Saturn. The planets acted differently (they had orbits) than the stars, and so were considered gods. Each planet had its day. Sunday was a day in honor of the Sun god, Monday was a day in honor of the Moon god, and so on to Saturday, which was a day in honor of their god Saturn. There were seven days in the week because there were seven gods to be worshipped.
Now the ancient Hebrews did not have names for the days of the week. This is critical evidence, because they have names for everything else, such as months, and seasons, etc. Why wouldn't they have names for the days of the week? If Genesis had come first, that would have been what what was expected. Some have argued that the Hebrews did not name the days because these were considered gods by the surrounding nations, and they did not want to give any honor to these gods. This is the same with Genesis. The days of the week certainly had names when Genesis was written, but these names are not included because they were gods. Therefore it is simply called "the first day", and "the second day", etc.
Genesis, by this viewpoint, is not written as a creation account, but is written as a refutation to the surrounding nations as to who created the world. It wasn't the seven gods of the Sumerians, it was the One and only God of the Hebrews. The acts of creation on each of these seven days are direct stabs at the supposed responsibilities of each of these gods. The sun god was responsible for light, but alas, it was Yahweh who created the light, not the sun god, therefore showing that Yahweh is everything, and the sun god is nothing. It works the same with the other days of creation.
There is much more to be stated on this theory, but I have given a broad overview, and I hope it is understandable. Please let me know your thoughts.