If you have a homebrew running software like M3 Micro, or Supercard, than yes. If you get one of these you will also need the Passcard 3. Or you can go with the DS-Xtreme.
plz list all the things i need to be able to play homebrew and downloaded games. and do i need to be at any version?
For the original DS: M3 MiniSD Passcard3 MiniSD Card Card Reader For the DS Lite: M3 Lite Passcard3 MicroSD Card Card Reader For both the Original DS and DS Lite, but might lack some homebrew for awhile: M3 Simply DS MicroSD Card Card Reader