^^lol^^ "is my ds an animal?"
But yeah I am a pretty new modder myself, and for 15$ I got an iron from radioshack that is dually watted where you cna use 15W or 30W. O and yeah a 20 watt will be ok just make sure when working with your ds do not keep the iron touching the board for mroe then 2 or 3 seconds at a time, I wouldn't even really recomend 3 seconds with a 20 watt, but it might still be ok I guess. 15W is better though for a beginner, or really anyone if you working on boards like that.