Since you're using your ds, you should save money by buying an ezflash cartridge and using GbaExploader to load roms. This also makes it so you don't have to use any wires and shit, you just put the roms along with gba exploader app on your ds flash card and put the ezflash thing in your ds and never have to take it out.
The flash cart looks like this
and gba exploader is here
You have the option of loading the games just as they are temporarily onto the card right then and there, or to run them in "nor" mode, which means that the rom will be loaded onto the cart as it's "main" game, occupying the cart as if the cart was an actual copy of the game, meaning that if and when you take the cart out and put it in a normal gba, it will play the game that was loaded in nor like a normal copy of the game. It would be great if every game could be loaded temporarily, but games that are over 16 mb (e.g. Mother 3) are too large to occupy the "temporary" part of the cart, and, while still playable, must be loaded in nor mode.
Hope this helps.