The SD1100 IS is probably built better. It has image stabilization, and a tiny viewfinder which is handy for when you can't see the LCD.
The A2200 has a much wider angle lens for landscapes or group shots indoors. It can take 720p HD video, and accepts AA batteries.
I lost my camera on vacation and 2 of my friends offered their old cameras.
The choices are above in the title.. so which one should I choose??