You'll have to sign up next time Emily, or so help me I will fly to America and do it for you!
and then stuff you in a suitcase and smuggle you back to New Zealand. =]
Hmm, did you have to use an instrumental version. I'm just trying to remember the talent show my school had a couple of years ago, I think they just sung over the original artist's vocals.
I mean, if your mike was loud enough... nah I have no idea. Sorry, I'm a crap in the whole advice-giving, wisdom kinda thing. =/
But seriously, you have to have a go next time. Instrument accompaniment or not, I'll bet you'll be fantastic.