Small digicam with SLR capabilities?

I have a D50 that I absolutely adore...but nearly wanted to chuck the thing when I went on vacation and had to lug it around the city. I'm looking for a smaller, purse-sized camera that still puts out quality, professional images...are there any which have shutter/aperture-priority/program modes? And very high ISO settings?

I will disagree with the other posters.

At the high-end, the Leica M8 is a compact camera capable of making professional quality images, it has high ISO settings, and even interchangeable lenses.

Most likely, it's out of your price range, but nevertheless, the camera you describe in your request does in fact exist. And depending upon how much you'll tolerate as a professional/quality image, there are others.

For example, the Canon G9 is smaller but does much better than a run of the mill point and shoot.

Not to mention, even disposable film cameras can work; just have the images developed and scanned to a CD.

For really compact high ISO shooting, the Fujifilm F50fd is pretty good, but a lot of people actually prefer the older Fujifilm F31 camera for high ISO shooting and compactness. The problem is that the used market for the F31 has driven the price to astronomic levels.

Sort of. They won't be quite as nice as your "real" camera, but the features you want are there. For example, Fujifilm just released a Finepix F100 that goes up to ISO 3200 at full resolution and higher ISOs at reduced resolution.

No such animal ... think of carrying around your D50 and lenses as cross training. I lugged a D100 with three lenses all over the Caribbean for over two months ... I used a backpack and after a few days, I just got used to it.

The problem with "small" digicams is the small sensor size and no lens interchangeability.

The Nikon D40 is the smallest Nikon DSLR made and might satisfy your want of a smaller camera (visit a camera store and hold one in your hand)

http://www.dpreview.com/reviews/compare_...
http://www.kenrockwell.com/nikon/d40.htm
http://www.kenrockwell.com/nikon/d50.htm

fhotoace is right, the nikon d40 is a very small camera that could be easily lugged around.

Although if you're looking for something that's a point and shoot I might take a look at the Panasonic Lumix series with a huge optical zoom on them.