smartDraw and alternatives

[Viktoras Didziulis]

what software for easy drawing eye-candy diagrams (Tree diagrams, ER, block
diagrams from templates) do you usually use? I tried smartDraw (www
smartdraw.com) but for some reason it is very unstable and almost unusable
on my system, so decided to ask for your advice again on comparable
alternatives (MacOSX, Linux, Windows). Thanks in advance! 
 
Regards 
Viktoras