In order to download Calculator programs to your calculator, you will need the following things.
These are all that is needed to transmit programs to any TI calculator supporting programs. The software can be downloaded for free from TI, and you can probably buy a cable from them, too. Keep an eye out, though. I bought mine at Office Max for $14.99, and TI was offering a $15 mail-in rebate inside every package. Good deal, eh? (Regular price is something like $20.)
To edit, or view the programs on your computer, you will need the TI Graph-Link Software, which is specific to the model of calculator the program is written for. Download that software here.