|Choice doesn't set a variable it sets an errorlevel.|
The errorlevel set is in relation to the characters position after /c:, the errorlevels will count up from left to right - /c:123456789.....
Since your using xp you can just use "if %errorlevel%==number <stuff>". You can also do things the old way, especially if you want the script to work in dos based systems. The thing to rember doing the errorelevel check is that you start from the highest number and work down.
if errorlevel 3 goto x
if errorlevel 2 goto y
if errorlevel 1 goto z
In your situation it would be:
if errorlevel 2 goto exit
if errorlevel 1 goto delete
Forgive me if I have made any mistakes, this is from memory, I am currently on a linux box.