I'm going to buy a digital camera.plz help me:CANON SD500 or 350D?

They are 2 totally different kinds of camera. Point-and-shot vs DSLR. With the 350D, you'll have the flexibility to change lenses for different kind of situation. And because of that, you will most likely spend a lot more money than just getting the SD500. If image quailty is important to you, go for the 350D. But if easy to use and compact size is what you perfer and you have no intention to get into photography, the SD500 will be a better choice.

http://www.dpreview.com/

I use a Canon SD630 and absolutely love it. I preferred the larger screen (3") . I like the digital models and highly recommend the Canons. I have used many and they are the best.