Now THAT'S an interesting one.
However, the dogfighting rule of thumb is
energy is life. In other words, how much speed you have or potential energy from altitude that you
can turn into speed.
Corollary to that rule is
rate kills, ie how fast you can turn your crate to get guns on target.
Turn Rates for Various Fighters
Spitfire Mk XIV Performance Testing
Note that the airspeed here is in KEAS. We'll also take the Spitfire to be Mark XIV, which could do around 448mph with a 2000hp engine.
A-10 Stats
USAF A-10 Fact Sheet
Now we know where intelgurl got her pic from!

Unfortunately, no turn rates! However, the USAF says the aircraft is "slow but maneuvrable."
So, saying that speeds and acceleration are roughly equal, and perhaps with the Spit having the faster turn rate, we can say that the Spit has better
odds of getting on the A-10's tail. So what then? The Spitfires twin 20mm cannons will have a tough time carving up the beast! The A-10 isn't called
"the flying tank" for nothing. The Spitfire can probably carry on firing until it runs out of ammunition, unless it damages both engines or manages
to hit the cockpit and kill or injure the pilot - he / she's only protected from ground fire by that titanium bathtub.
An even match, but the Spit pilot will need to be a very good shot to come out on top... and we don't need to wonder what will happen if those 30mm
DU rounds stare coming the Spit's way...
[Edited on 17-11-2003 by Lampyridae]