well it depends on what you are after. If you are going to be making your own games and selling them I would suggest garage games route. If you are after just being employed then its basically how quickly you pick this stuff up.

have you thought of mobile phone development or maybe the iphone/touch? There used to be a lower barrier to entry to get jobs doing these sorts of games. Also easy to learn j2me and build your own engine on it.

my only caution about the DS is effectivelly you will never be able to release a game on it but on the other side a cool tech demo on a ds would get your foot in the door with a devshop doing ds stuff.

good luck with it.