think the real question is, does the audi come with a warranty?
personally, as someone else mentioned, a new car instantly depreciates, so not alot of point in getting one there!
plus id just go for audi anyway... quattro, reliable, nicer looks imo
Definately go for the A4, personally I think they are a LOT better looking and probably have a far better resale value for when you come to sell it. Check out some prices here http://www.usedaudia4.com
Have you driven either car yet? It's one thing for us to suggest a certain car, but it is another for you to get behind the wheel and get a feel for the vehicle.
How much is the Audi selling for? I've driven a 2008 A3 a few times and loved it. It is one quick car. The A4 is even nicer.