Support for PNG in Browsers

Does anyone know about how well PNG images are supported?
I have a web app that creates dynamic images. At the moment it outputs them as JPEGs but they would be better as GIFs. I'm avoiding GIF because of the patent problem.
The JPEG dithering is beginning to get me down, but I'd prefer to have some idea on the percentage of viewers that will be able to see the images.
Anyone?

look at:
http://www.libpng.org/pub/png/pngapbr.html
http://www.w3.org/Graphics/PNG/
and
http://www.libpng.org/pub/png/pngstatus.html#browsers
By the way, I tried just couple days ago to create a servlet, that will generate an image.
That image suppose to be 2 pixel height and 1 pixel width (I wanted it as a background color for table cells). Url for a servlet suppose to contain 2 parameters - colors for both pixels.
I just gave up - it messes colors even if I set quality to 100%.
I mean, if I provide 0000ff and ffffff they both get changed - blue is not exactly 0000ff and white is kind of lightblue. If first color is green, than white is kind of lightgreen.
If anybody knows, is it how it suppose to be, or I made some stupid mistake, please respond.
This is the code:
String strCL1 = request.getParameter("color1");
String strCL2 = request.getParameter("color2");
int color1 = 0;
try{
color1 = Integer.parseInt(strCL1,16);
}
catch(Exception e){}
int color2 = 0;
try{
color2 = Integer.parseInt(strCL2,16);
}
catch(Exception e){}
BufferedImage img = new BufferedImage(1,2,BufferedImage.TYPE_INT_RGB);
img.setRGB(0,0,color1);
img.setRGB(0,1,color2);
ServletOutputStream out = response.getOutputStream();
JPEGImageEncoder enc = JPEGCodec.createJPEGEncoder(out);
JPEGEncodeParam param = JPEGCodec.getDefaultJPEGEncodeParam(img);
param.setQuality(1.0f,true);
enc.setJPEGEncodeParam(param);
enc.encode(img);
out.flush();
out.close();
[ April 06, 2003: Message edited by: Yuriy Fuksenko ]

Your code is like mine, and I'm getting the JPEG dithering too. Interesting that it dithers when there are only two pixels...
Thanks for the links, I'll check them out.

Well, I had the same effect, when I tryed to create 30x30 pixel image, but only with 2 colors, alternate for each pixel line.