I've had good luck converting Microsoft Office charts to OpenOffice.org in 1.x of OpenOffice.org. The issue might be how the data is created that the chart is based on. If it's created from macros, then the resulting chart won't work.
Unfortunately, OpenOffice.org 2.0 still will not automatically convert Microsoft macros. However, based on my classroom experience, some of the features that people use Microsoft macros for can be accomplished in OpenOffice.org without macros. So while one aproach is to keep a few licenses of Excel around to run documents containing macros, another option is to evaluate whether some or all of the macros are necessary.
This was first published in October 2005