With the Data Import Wizard you can specify to start importing at a
particular row. However, the maximum this can be is 32k (32768), so
this allows you to import up to 96k records in two passes - the first
pass will get the first 64k rows and the second pass will get 32k -
96k. You thus have the rows 32k-64k in both worksheets, and you will
need to delete the duplicates.

If you have files with over 96k records you will need a different
strategy - you could load the file into Access and then split it from
there into Excel-sized chunks, or try the same with Wordpad, or you
could use Quattro Pro or Lotus which will accommodate up to 1,000,000
rows.

Alternatively still, Microsoft posted a macro to work on large files
and automatically split them into 64k sheets - I don't have the
reference myself, but you could search their Knowledge Base articles.

Hope this helps.

Pete