One Database? Multiple databases?
Uses repeating fields?
If one database without plugins, and without repeating fields, it is likely that the conversion would take less than a minute and be painless.
The trying would be the proving.
The Computer Guy, Seattle
all their payroll information is stored in an antiquated copy of Filemaker Pro (version 5 I believe) and they want to make sure that it will all transfer over.
There is no reason why the data couldn't be preserved perfectly. Filemaker 10 can convert .fp5 files and import from them. To be absolutely safe, export the data from the existing files into a text format (XML is best for this, as it preserves both field names and types).
How well the converted files will preserve their functionality is another question.