First i must to thank you : i never known this difference between FMP for Mac and FMP for Windows. However, i work on a Mac and have customers on both platform.
Anyways, i have some good news for you : with FileMaker 12, this difference between Mac and Windows doesnt' exist anymore.
You will found here a post that was prior to v12 version and confirmed the previous behavior :
This is a known difference corrected with the release of Filemaker 12.
I dont' have version 7, but when I pull down the Edit menu in FileMaker 11 after copying, the paste option is clearly labeled: "Paste unformatted text".
Thanks to both of you for your responses. I'm definitely going to get the new version of FileMaker--much cheaper and easier than replacing my computer!
You may find this information helpful in converting your current files to FileMaker 12 format.
Converting to .fmp12 format: http://help.filemaker.com/app/answers/detail/a_id/10571/kw/converting
Be prepared to invest some time into testing and updating the converted files as there is a good chance that your converted files may not function perfectly. The KB articles cover many, but not all of the possible issues. Feel free to post back here with any issues you encounter that don't seem to have been covered by the KB articles.