I loved my S330 (2 Mp). I sold it yesterday and i'm probably going to buy a S410 to replace it. I like that i can put it in my pocket, and i thought it took great pictures. The S410 is slightly smaller, which is nice.
I too had a similar problem in selecting digital camera, but i went for ixus 430...and man, its worth every penny, the good thing is that it packs all the punch that a good camera can offer in a compact box, its really good camera money can buy.
Don't go for anything below ixus 430 the i and ii series are old, and its not worth going for them.
I'll recommend you to go for CANON DIGITAL IXUS 430, its the best bet