Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
There's plenty of ways to convert Microsoft Office 2007 file formats (.docx, .xlsx, .pptx) to OpenOffice.org. Now OpenOffice.org 3.0 imports these Office OpenXML files natively, but natively doesn't mean a fluent translation.
Any translation is subject to imperfections. For OpenOffice.org 3.0, it is the first public release of the Office 2007 converters. Overall, it is very good, but it stuggles mainly in areas related to tracking changes, comments, tables, and drawings. You can wait for OpenOffice 3 to mature, but there's another way for the impatient.
Knowing OpenOffice.org 3.0.0's weaknesses, I designed a .docx document specially to torture OpenOffice.org and to point out its weaknesses.