explorador - 5:06 pm on Apr 24, 2013 (gmt 0)
Of course, retaining the original URL (example.com/page100.com) for the pages transferred to Drupal would be paramount.
You can use your old URLS if you want to, it depends on how you import the data, there are diff ways, I tried several and ended up doing a manual export - import. Even cleaned up the content before :)
Anyway I migrated thousands of pages with their old URLs to new drupal installations. Check here:
If you already have your content on drupal you can still easily import only the url maps. Not as difficult as it sounds.