Launch 0 Newbie Poster

Hello, I'm creating a program that functions as a piano in Microsoft Expression Blend and I've hit a bit of a bump.
I'm very new to XAML programming, so I thought I'd ask for help since Google searches for the answer just send me deeper into confusion.

Basically, I have a JPG image of a piano like this.

And each key has a button on it, that when pressed plays the appropriate tone. That seems to work right now. However, when I press a key, it plays the entire sample. It doesn't stop when another key is pressed. As well as this, I'd like it to play the sound when the button is held, then play another ending sound when the buttom is released.

I've tried using the MouseEnter and MouseLeave EventTrigger, but the MouseEnter sound plays in its entirety instead of it being interrupted by the MouseLeave trigger.

Any help would be appreciated.