color border became thicker after converting to pdf

Hi,

I am having some problems that after converting my sheet to pdf, all the colored borders became thicker than those i previewed in excel.

I dont know if this results from my excel file or my pdf converter. I tried with PDFCreator as well as the one under adobe acrobat and i still get the same result. I am using both excel 2003 and 2007.

I would like to have the same look in pdf as what i see in excel print preview

Could you please advice how to get this fixed?