Oyster Card vs. London Travel Card?

I will be traveling to London, England from Orlando, FL. The dates I will be there will be from November 19-November 28, 2010. I will need to transport to and from the London-Heathrow Airport to my hotel (not sure exactly where yet) in London, and will be traveling all around London for the remainder of my stay. I've been reading into the London Travel Cards and the Oyster Cards and I am still confused as to which one would be the best option for me. I won't have an itinerary, so I'll pretty much be touring around the city and going where my own will takes me. I just need help figuring out which card would be the best for me to choose. I would (for the most part) like to stick to using the tube stations and the buses. Please help me! Thanks!