aNdY wrote:

> why is Canon EOS 5D so expensive?

Because it has a full frame sensor.  Bigger sensors are harder to make, 
therefore more expensive.  Also, it's aimed at professionals so they may be 
keeping the price artificially hight.

> Canon EOS 350D / Digital Rebel XT  & Olympus E-500 - which is better?

Take a look at these pics;
http://www.dpreview.com/reviews/olympuse500/page20.asp

I'd go for the 350D.

Paul