The amps in those beginner packs usually sound pretty horrid. Don't worry about whether you sound like this guitarist or that, because that's not important right now. What is important is that you learn how to use the gear that you have, and learn to get the best out of it. Also, use this time to concentrate on your playing technique and style. That will have a big impact on how you sound. Slash would still sound like Slash playing through your exact gear, and a beginner would still sound like a beginner playing through Slash's exact gear. Try not to get caught up in the never ending search for the perfect tone. It will never stop, and you will cry when you realize how much money you actually spend on your search. Trust me, I know :( . Focus on your playing now, and your tone later.