Canon Ixus 40 vs Ixus 500

I had made up my mind to buy an Ixus 500, but now I've been reading about
the Ixus 40 and I'm torn between the two.

The Ixus 40 seems to have several advantages over the 500 that I like the
look of, in particular:

Much larger LCD (despite the slightly smaller camera size!)
Faster operation (and supposedly better image processing) due to the DIGIC
II processor
Several scene modes, such as a "night snapshot" mode that I would probably
make use of
Unlimited time 30fps VGA movies (as opposed to 30 seconds maximum, 10fps)
Use of SD cards rather than CF cards

The only things that are making me hesitate are the apparent disadvantages
regarding image quality:

1/2.5" CCD rather than 1/1.8"
4 Megapixels rather than 5

I mainly just want to get good quality normal sized prints (from a
professional lab, not printing myself), but would like the option to print
enlargements to about A4 size. Am I likely to see much of a difference in
quality? Do you think it would be a mistake to "make do" with the smaller
sensor and lower resolution to gain the improved features?

I'd be interested to hear anyone's experience of the Ixus 40, especially in
terms of picture quality.

Thanks!

I had made up my mind to buy an Ixus 500, but now I've been reading about
the Ixus 40 and I'm torn between the two.

The Ixus 40 seems to have several advantages over the 500 that I like the
look of, in particular:

Much larger LCD (despite the slightly smaller camera size!)
Faster operation (and supposedly better image processing) due to the DIGIC
II processor
Several scene modes, such as a "night snapshot" mode that I would probably
make use of
Unlimited time 30fps VGA movies (as opposed to 30 seconds maximum, 10fps)
Use of SD cards rather than CF cards

The only things that are making me hesitate are the apparent disadvantages
regarding image quality:

1/2.5" CCD rather than 1/1.8"
4 Megapixels rather than 5

I mainly just want to get good quality normal sized prints (from a
professional lab, not printing myself), but would like the option to print
enlargements to about A4 size. Am I likely to see much of a difference in
quality? Do you think it would be a mistake to "make do" with the smaller
sensor and lower resolution to gain the improved features?

I'd be interested to hear anyone's experience of the Ixus 40, especially
in terms of picture quality.

Thanks!