Something that Rick Lyon talks about on his website is that if you wanna be a puppeteer, you have to be a good performer, a good actor, and a good singer. This was Jim Henson's legacy; he set the standard for puppetry. Truly respecting the art means WORKING HAARD. He literally sez to "practice until your arms fall off... and then practice some more."
Like everyone's saying, if ur heart is in the puppet(eheh, not LITERALLY
), and you really love what ur doing, that can transcend natural ability or lack thereof. Someone with a really nice voice won't be convincing if he/she hates puppetry! Also, a CD dub isn't what I'd recommend, being the purist I am. It just doesn't do justice for the performance, OR your self confidance. So keep up your passion for puppetry, and never never give up!
Greedo