burning-half-the-deck problem

[Felipe]

I'm trying to convince someone that I'm right (what else is new ...) I'm using the following example to explain how (some) probabilities work in an ordinary texas hold'em poker hand (or any other poker hand, or any other gambling game for that matter.)

Problem:
* You take a standard 52 card poker deck.
* Remove two Aces and set them on fire! Burn 'em!
* Shuffle the deck
* cut the deck in half, without looking at any of the cards, and set it on fire too. Burn it!

The probability of the top card being an ace (in the undiscarded half) is 1-in-25. My friend thinks it's 2-in-25. How can I prove this to her?!?!?! It so irritating that I am unable to explain it to her further.