X4 should be able to open most files back to version 5. Anything older is probably best opened in the original version and saved to PDF by printing to a PDF print driver (foxit, bullzip, acrobat etc). You will then probably be able to import the PDF into X4 or X7.
X7 should be able to open most files back to version 7.
2002 is quite recent in Corel history -- the current version was 11 -- so unless you were using a much older version back then, that ought to cover the files you have.