Quite a few people have wondered how to argue Evolution and the age of the Universe with fundamentalists who insist everything popped into being in 4004 BC. My solution is to blindside them with a few Astronomical facts.
We start with the fact that all stars have an 'apparent brightness' -- how bright it appears to us, and an absolute brightness: How bright it would appear to be at a set distance (10 light years, in this case). If you happen to know exactly how far away something is, you can determine its absolute brightness from its apparent brightness. If you know the Absolute brightness, you can determine how far away it is by its apparent brightness. Both of these work with the basic physics law of Inverse-Square: A light source with brightness X, Distance Y away has 1/4 of that brightness when twice as far away, 1/9 at 3 times, and so on. Make sure your wingnut agrees with this simple, obvious physics.
Next, you bring up Cepheid Variables
http://imagine.gsfc.nasa.gov/docs/science/mysteries_l1/cepheid.html
http://zebu.uoregon.edu/~soper/MilkyWay/cepheid.html
These stars vary in brightness in regular patterns (the stars are essentially 'breathing.' -- growing larger and smaller in a set pattern) The time period for all Cepheid variables is the same for a given brightness. That is, if you took two of these stars with the same time-scale variation in brightness (say, 3 days from brightest to dimmest), and looked at them from exactly the same distance, the average brightness would be the same.
This means, no matter HOW far away a Cepheid is, we know exactly how BRIGHT it is, and from how dim it appears to us, we can determine how far away it is, again from the inverse-square law. Get the Fundie to agree again. (almost every fundie does)
Then see if they will agree that Galaxies (like the Magellanic Clouds companion galaxies to the Milkyway, and more distant galaxies like the Whirlpool Galaxy and Andromeda) are far enough away that every star can be considered the same distance away from you, much like you could assume, if you're standing in Los Angeles, that everyone on the island of Manhatten was the same distance away from you -- its not exactly true, but its well within the margin of error. They should basically agree with this idea as well.
Point out that point out that with modern, very large telescopes like the 200-inch Palomar telescope, and high tech telescopes like Hubble, we can resolve distant galaxys, like Andromeda, into individual stars. further point out that we can see Cepheid variables in these galaxies. they confirm that Andromeda is 250,000,000 light years distance away. That means it takes light 250 million years to reach us from there.
So, you ask, if the Universe is 6000 years old, how come we can see Andromeda?
this should set them stammering, since they are not expecting this attack on their beliefs! Worse (to them): They agree with everything leading up to your question! They suffer brain melt.
(edit)
The only defense they have left is 'God created the universe 6000 years ago with all that light -- even the 13 billion year old light from Quasars -- already on the way.'
To which, the only proper response is "So, you're saying God asks us 'Who do you believe, me, or your own eyes?'"