As long as your database doesn't use any unusual fonts not installed on the other computer, it should transfer pretty smoothly. If you did use such a font, the database will open and function ok, but some layouts may look different when filemaker substitutes a different font. In some cases the layout may need adjustment to correctly display the text.
A no cost test of this would be for your PC owner to download the free trial version of FMP 10. Then you could email them a copy of the database and they could see what happens when they use the trial copy to open your database.
Thanks for the advice! I will have my friend download the trial version.