Another, new, Powershot?

Hello.
I'm wondering what my next camera should be. It will really be my third, so I want to make sure it will last a while.

I've had an HP MX220, very low grade with only digital zoom. Then I bought my current camera a year or two ago, a Canon Powershot SX100IS. It takes good pictures, but I'm afraid the autofocus has gone bad. Zoomed in far, there is a lot of color noise even at the fastest of shutter speeds. Its annoying.

And while it does take good pictures and has a 10x optical zoom, the noise kills me. I want to take extremely crisp photos that look good even enlarged. So I need suggestions. Maybe, buy another, better Powershot? Or look into a different brand.

P.S. I have a max $400 budget. Not much, but I'm just starting my 2nd job and its all a 15 year old can cover. x]