Downloaded games on my DS

right sorry in advance if this is covered elsewhere, i cant find a complete answer so i am going to ask myself. Can I purchase an M3 DS Simply and a microSD card ( to put in the SD card ), and a usb card reader. download nds games from the interweb, drag and drop nds files to the SD card, place the M3 into the ds slot one, power up the ds and away to go, i can play copies on my ds. or is my idea on how to do it completly wrong, if so where have i gone wrong and how do i put it right. p.s. where can i find the cheapest way to do this, in the UK ( damn, that sounds cheap ). thanks in advance