The free version has too much latency, you could try to compensate for it by moving the vocal track back but thats a pain in the ass.

I would recomend the Protools MBox (can get one for around $420). It includes the ProTools LE software. You also check into, Cubase (there is a light version available), or Bias Deck. Any of those will do the trick for you. Don't be suckered over to a PC....the misconception that there is no software for the mac is false.....I've got more than i will ever use. (I use a Digi001 protools setup).