Noob question: Step down regulator

[Arc64]

Hello, I'm going to start my first N64 portable in the coming weeks. I have some experience with soldering and electronics, but this is the first portable I've attempted. Anyway, this is my question: I know I need a step-down regulator, and I've gathered a basic idea of what this is, but I don't know what specific kind I need or where to get one, and the majority of pages I've found on Google about the subject have been pretty labyrinthine. What is the specific kind of step down regulator I will need and where can I buy it? Thanks in advance, and sorry for the unspecific question.

Edit: For example, would this be what I'm looking for? http://www.parallax.com/Store/Component ... roductName" onclick="window.open(this.href);return false;

I know most people recommend the PTH08080, but I can't find where to buy that.

[Oracletriplex]

You can get them as free samples from Texas Instruments web site. Or order the equivalent from Digikey.

[Arc64]

There are a few different models; which should I order?

[hailrazer]

There are a few different models; which should I order?

It doesn't matter. They are the same just a different pin arrangement.

[Oracletriplex]

There are a few different models; which should I order?

I ordered one of each. The pth80808waz, the pth80808wah, and the pth80808was I think.

I know it costs TI fifteen dollars to ship them, but I consider it an investment in my electronics education. Thanks, TI.