I recently came across an old and surprisingly even-handed Time article on the Bible and archeology. It's a quite readable piece and reminded me of some things I wanted to say about the topic here.
1) Lack of proof is not disproof.
Just because we haven't proven someone or something existed, that doesn't mean we know they didn't. I doubt we'll ever have proof Abraham existed. A few thousand years from now, there probably won't be proof Bill Gates existed. Archeology is limited to what we find, and what we can find is limited to what survived.
2) The experts are often proven wrong.
There are a number of things in the Bible every "expert" once knew to be fiction that has since been shown to be factual — e.g., the existence of the Hittites or King David. There is no point in getting worked up about archeologists saying something or someone didn't exist.
3) Archeology isn't an exact science.
Archeologists find bits and pieces that survived the ravages of time and try to reconstruct the world of thousands of years ago. Many of their conclusions are based on assumptions that may later be disproved — e.g., that this Egyptian king corresponds to this guy mentioned in an Assyrian record which is used to date the Exodus out of Egypt. It's not fair to say they're guessing, but there certainly are huge error bars on some of their assessments.
4) Use with caution.
As interesting as this stuff can be, and as illuminating as it occasionally is, we don't want to push it farther than warranted. I wouldn't put to much weight on any "proof" or "disproof" that comes out of this field.
That said, we have learned some very interesting things from study of the distant past, things that can shed some light on the OT. I hope to share some of that in the not-too-distant future.