Hi Beauty
Limewire basic is free from
www.limewire.com
You will have difficulty hiding it .. well it is impossible unless you totally uninstall it after every use. Also it is worth mentioning that many files downloaded from Limewire contain viruses and spyware, and if any of these things were to mess up your Dads computer he would do more than trip.
There are many files that are quite legal to download with Limewire many others that are not legal ... now should it be that your dad got into trouble for you using Limewire for the wrong purposes, he would again do more than trip. It is his computer, and I think you should talk this through with him. You might have guessed I'm a Dad myself ... so I'm a little on his side and also don't want you to end up fighting, or destroying his computer