Both Filemaker 8.5 and 10 use the same file format. Both windows and mac versions of filemaker use the same file format. Thus, you simply have to copy the files from one computer to the other. Exactly how you do that depends on your computer set up and the size of the files to be copied. If they are both on the same network, this can be as simple as dragging the file from one computer's hard drive to another.
Thank you for your reply, Phil!
Do you know what files I need to copy from the Mac to PC (is it just the a flat database file or is it multiple files - I have a customized database and layouts on the Mac)? When I looked on the Mac I didn't seem to be able to find the database file(s). Do you know what the default database path is on a Mac with FMP 8.5?
You could have multiple files or a single file.
Check to see what's listed in your window menu when you have the database open. These window names are very likely the filename or names to your system. Then use the Mac tool for finding files and search for these names.