I came across Microsoft Chart Controls for Microsoft .NET Framework 3.5
I think Microsoft has made a good move on this and having looked at the samples and used it in a small project.
Its
See more here
One error i came across was : The temp directory in chart handler configuration is not accessible 
And what it is when you look in to your web.config  you will find this TAG in the appSettings:

<add key="ChartImageHandler" value="Storage=file;Timeout=20;Url=~/tempImages/;"/>

When you drag the Chart control into design mode it adds the tag above to the web.config and you shoud have a folder called TempImages.

You get the error when its trying to right or modify that folder and all you need is to give the folder the right access.

On my Vista machine i just gave  COMPNAME\Users write and modify access and bingo it worked
But i reckon you mght need to give IIS_WPG(COMP_NAME\IIS_WPG) access too maybe on other OS

Hope that helps and enjoy using the charts in your Apps