From the version 3, MS-Works should be able to read the files from the other platform. We don't have enough experience yet.
Before, you had to convert files to something the target application could read.
You had to save spreadsheet files to Excel, Lotus 123 or Sylk.
Data base files had to be saved as comma (or something else, tab, quotes) separated files (CSV and several other extensions). Text files had to be saved in something the target program can read, mostly "text only".
If you only have text files to transfer from the Macintosh to the PC, you can do everything from the PC. A demonstration version of our MacText utility can be downloaded from this site. This little converter only handles text files.