Without knowing exactly how the files are named, any code I could give you would probably not function as intended.
cb60373-01 Kenny Chesney - When The Sun Goes Down.zip
They all being with cb followed by 5 numbers then a dash then two more numbers? If so, then this is fairly easy to do. If not, it would be more work but still doable as long as there is some type of pattern to it.
Edit: Assuming the above is true, you'd could use something like...
Pseudo-code
test file to make sure its something you want to change
set a variable to capture everything but the first token
replace .zip with (CB).zip
rename the file to the variable