[pdftex] fancy graphs

[Luca Bortot]

I apologize in advance if my question is more tex-related than 
pdftex-related.

I am trying to draw some graph with pdftex.
I don't need gradients nor textures nor shadows nor any complex 
graphics, just circles and lines.
But I would like to have at least colored, filled circles and (but this 
is optional) lines of different thickness.
What is the easiest way to achieve this? Pdftricks? PicTex? Any simpler way?

I'm sure there is something I don't know in color or graphics package 
that can do the job...

thank you,
Luca Bortot