Thanks guys for all your replies.

It's true- Singer is really important. For a definite amateur, I think I can impress some of unexpecting friends, but in front of 50-75 strangers/co-workers (the size of the 'unpaid' gig)....I'm not so sure.

I don't think anybody there are into Hip-Hop (when I think hip hop, I'm thinking Janet Jackson...was I mistaken?)

One more thing- There's one song from Shania Twain that I only know this part when she shings.."aaoouuuuu...naa.naa.naa..naa.naa..na.naaaa..." (along with the singers at the end). I can't get that part out of my head but I've searched high and low but can't find it anywhere.