[Rob Barron]

In my personal opinion, no, they can't. The picture quality from a DSLR will be higher both down to image resolving capability and internal processing.

Having said that, you don't seem that bothered about the best quality images as you said you only look at them on a monitor anyway. That means you are fine with images that are low resolution. So, let's say you make a picture nice and big to show on your 19" monitor. I assume you don't to scroll around all over the place to see the full image so a 12" x 8" image is likely to be the sort of size. At 72 dpi that is just 864 pixels by 576 pixels giving a total pixel count of 497,664 pixels. In other words less than 0.5 megapixels!

Frankly if that is definitely all you are going to ever display your images on, I would definitely go for the A640 as you really don't need any more and that camera is a perfectly respectable camera. I think I'm right in saying it uses the same Digic II processor that the 400D uses as well.

I think you will be perfectly happy with the image quality of the 640 so my suggestion would be that you go for one of those. If in the future you decide you really want to go the SLR route, you can always upgrade and sell your A640 for a reasonable price without losing too much.

Cheers,
Rob