Been using FileMaker on windows systems since the release of FileMaker 3. You can copy your files across and open them without any special conversion IF you have a windows version of FileMaker installed on your windows machine. Whether you can find or purchase an older version of FileMaker such as FileMaker 11 or not is the question that I cannot answer for you.
Good news. I'm sure there will be a solution then, whether it's a cross- or up-grade... I'll try and contact the UK office and see what it will cost me. (Always the bottom line for the little guys!) - Neil
If you received the FMP Install CD, it has both Windows and Mac installers.