if you want take night shots you need a camera that can set manual shutter speed for more flexiblity. Also the ability for the camera to gain up in dim lighting would be good. Another feature you need is AF lamp as this speeds up forcusing in dim situation. If out of the 2 you should chose go for canon. If you want just something easy go for Fuji F10, got high ISO with lower noise compared to others. W5 would be good too if on budget and can stand the slightly bigger size. I'm using Sony W1 and would recommand it to anyone not going to print big big prints
From what I see, the canon one can go up to 15secs of shutter while T1 only 1 sec. I feel the canon has more manual functions (if its the sd400). But even the T1 can take a decent nightshot, once u master that camera but perhaps the sd400 has an edge 15secs is more than enough. I luv nightshots too.