What is a good digital camera to buy ??

Depends on if you want a point & shoot, amatuer/professional, or full-fledged professional setup.

So for now I will recommend a Canon Powershot SD700 somewhere in the SD700 and up. This is a great Point & Shoot.

Canon 30D Digital SLR (great for budding amatuers as well as professionals)

Canon 5D or 1D for professionals who can spend a little more. It's more about the lenses though, unlike in film it's more about the body but the lenses are important as well.

Canon powershot is great. Nikons are good too. Don't get a sony or something cheap like that.

I like theSony Cybershot DSCW55 7.2MP Digital Camera with 3x Optical Zoom. It has a Carl Zeiss lens, and although Sony now makes a newer version, this one is great.
You can buy it on Amazon.com as well as lots of other places.

What sort of photograph do you want to take?

I have had four cameras...and Sony was the best brand so far. I would go with Sony

I would like to highly recommend the purchase of a Nikon Coolpix L10 for the following reasons:

1. Besides taking well-exposed hi-quality 5 megapixel pictures, it uses a standard set of rechargeable double AA batteries which last a very long time;
2. Has a 3x optical zoom;
3. The flash setting for "red-eye" correction is on the navigator wheel and not within a submenu;
4. It's very small and light;
5. Uses inexpensive SD memory cards;
6. The digital video feature takes wonderful "sound" videos which are noise free. It records the piano very well with it's built-in microphone;
7. It comes with a USB 2.0 transfer cable which you connect to your USB computer port;
8. And the price is a mere $120 [sold at Samy's Camera, Staples.com.]

Good luck!