About the only real difference between these two cameras is the wide angle (28mm) focal length on the SD800IS.
If you want wide angle....there you go.
Picture quality is very good on both and I would say identical.
The difference in megapixels will be hardly noticeable.
It does look like that new engine on the SD800IS has helped the shutter lag.
The SD700IS has a shutter lag of 0.3 second.
The SD800IS has a shutter lag of 0.1 second.
Here is a link to their specifications:
Want to buy a new Christmas camera and am strongly considering one of the Canon cameras listed above. I don't shoot movies, only still pictures. I prefer the additional zoom focal length in the SD700 (4.0)over the SD800 wide angle, although there isn't much difference since the SD800 has a 3.8 zoom and an additional 1-megapixel. The SD700 has the Digicam II image processor while the SD800 has the Digicam III. Both cameras seem to take excellent pictures. Is it worth the extra $50 to $75 to buy the SD800. Sure appreciate any info and advice anyone may have on these two cameras. Thanks!