I can't speak to the difference between Ex2k and Ex2k3, but I a couple
of things may be causing the numbers to import as text. Some database
programs concatenate an apostrophe before the entry, which Excel then
treats as text. Sometimes a leading or trailing blank space is
concatenated onto an entry during export, which excel also treats as
text. It's possible that neither of these instances would appear on
your screen, so you'd need to examine the cells by looking at them in
the formula bar to see if they exist.

If this is the case it suggests there's a problem with the export from
Lotus, rather than a problem with the import into Excel.

As a workaround you can insert a "helper" column, format it as a
number, and enter this formula for each imported value:
=VALUE(A1)
This will convert any text to a number.