An R4i card for your Nintendo DSi allows you to not only add games to the system with a microSD card, but it also allows you to add more videos, pictures, music and even ebooks. You can add videos, pictures and music with the microSD card slot already available with the DSi, but a second one in the R4 card will give you more space. An R4i card is an overall useful tool to have for your system.
Download the R4 software onto your computer (see Resources). Save the .zip file to your computer, right-click the file and select "Extract All."
Insert the microSD card into the USB adaptor and insert the adaptor into an open USB port on the computer.
Click "Open folder to view files" when Windows prompts you.
Highlight all the extracted files, right-click on them and select "Copy."
Open the microSD card folder, right-click anywhere in the folder and select "Paste." This moves all the files to the card.
Go to your favourite ROM website and download the games you want to add to your DSi. Sites like ROMulation, NDSROMs and ROM Freaks are popular (see Resources).
Extract the .zip files like in Step 1, and then copy the files to the microSD card like in Steps 4 and 5. Copy and paste any media files you want to add, as well.
Remove the microSD card from the adaptor and insert it into the R4i card.
Insert the card into the game slot of your DSi and press the "Power" button to turn on the device.
Select the PacMan icon for your list of games or select the music notes for media.