I had bought my Canon S10 a few years back now and its a 2.1 MegaPixel...
I have had 4x6'* done and they are better then when I had my Canon Rebel * 35mm.
I can print out a 8x10 and it comes out really good....
Safely get incredible 5x7'*
I think that 2.1 is the lowest you would want to go....3.2 or hight is probably your best choice at the moment.
All about $$$$
How much you want to spend?
Here is a pic I took with mine...for an idea of a 2.1 ( won't embed it for 56k users...LOL)