Forget the Nexstar and the P-51, you will be paying extra for stuff you don't need.

Look at the Hobbico Avistar instead, it is much cheaper, sturdier and many would say flies better than the Nexstar. With the money you save you can almost buy the FULL version of RealFlight. The flight sim software that comes with the Nexstar and the P-51 is very stripped down. Almost useless. You will likely end up purchasing the full version very soon anyway.

If you must have the stripped down software, you could look at the Hangar 9 versions of the Avistar, I think it's called the Alpha or Arrow. They come with the stripped down software and a trainer cord for the same price as the Avistar. The Avistar is a little sturdier than the Alpha or Arrow though.

The Avistar is about $260.00 or so and comes with everything except fuel and a glow starter. Learn to fly it and then sell it to your friends for nearly what you paid for it. Then you'll have money to spend on your new 2.4 ghz radio and warbird a little later, and you'll still have the FULL version of the flight sim software.